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UNIVERSITY OF NC AT CHAPEL HILL 



00015555926 




This BOOK may be kept out TWO WEEKS 
ONLY, and is subject to a fine of FIVE 
CENTS a day thereafter. It was taken out on 
the day indicated below: 




North Carolina 
Department of Conservation and Development 



R. Bbui e Etheridge. Director 



DIVISION OF MINERAL RESOURCES 
Jasper L. Stuckey, state Geologist 



BULLETIN NUMBER 41 



FORSTERITE OLIVINE DEPOSITS 
OF NORTH CAROLINA AND GEORGIA 



By 

Charles e. hunter 

Under the Direction of 
H. S. RANKIN 



PUBLISHED IN COOPERATION WITH THE TENNESSEE VALLEY AUTHORITY 




RALEIGH 

urn 



MEMBERS OF THE BOARD OF CONSERVATION AND 

DEVELOPMENT 

Governor J. Melville Broughton, Chairman Raleigh 

SANTFORD .Maim in. Vice-Chairman Winston-Salem 

II \kky BAILED Spruce Pine 

OSCAR Breece Fayetteville 

J. Wilbur Bunn Raleigh 

BRUCE Cameron Wilmington 

K. Clyde Council Wananish 

\\. J. DAMTOFT Asheville 

J. HORTON Doughton Statesville 

[RVING V. Hall Raleigh 

K<iy Hampton Plymouth 

J. L. HORNE, -Jr. Rocky Mount 

William Carl Hudson Morganton 

Charles II. Jenkins Aulander 

Carroll P. Rogers Tryon 

Richard Tufts Pinehurst 

R. Bruce Etheridge, Director 



CONTENTS 

Page 

Letter of Transmittal 8 

Preface 9 

Summary 11 

Introduction 14 

History of Development ... 18 

Review of Research ... 19 

Research in Progress .. 19 

Present Commercial Use .. 20 

Future Use of Olivine 20 

Acknowledgments and Field Work 21 

Regional Geology 21 

Geology of Peridotites 24 

Dunites and Saxonites 24 

Associated Minerals 28 

Serpentinization 30 

Steatitization 36 

Contact Metamorphism 36 

Weathering 38 

Description of Areas and Deposits 38 

Reserves of Olivine .. 38 

Table of Tonnages . 42 

Frank Area 43 

Frank Deposit 43 

Petrographic Analysis . 47 

Senia Deposit 47 

Other Deposits in Frank Area 47 

Toecane Area 48 

Day Book Deposit . 48 

Chemical Analysis 52 

Petrographic Analysis . 52 

P. C. E. Value 53 

Newdale Deposit 53 

Chemical Analysis 57 

P. C. E. Value 57 

Rakersville Deposit 57 

Other Deposits in Toecane Area 57 

Canton-Democrat Area 58 

Holcombe Branch Deposit : >s 

Petrographic Analysis 60 

P. C. E. Value 61 



I FORSTERITE I M.IVINK DEPOSITS 

CONTENTS (CONTINUED) 

Page 
Description Of Areas and Deposits — Continued: 

Democral Deposit 61 

Chemical Analysis 63 

Petrographic Analysis 60 

Juno Deposit (Serpentine) 63 

Petrographic Analysis 64 

P. C. E. Value 64 

Newfound Gap Deposit 65 

P. C. E. Value 65 

Hominy Grove Deposit 65 

Webster-Balsam Area 67 

I'.alsam Deposit 67 

Chemical Analysis 71 

P. C. E. Value 73 

Petrographic Analysis . 73 

Middleton Deposit 74 

Dark Ridye Deposit 75 

Chemical Analysis ... 78 

P. C. E. Value 79 

Petrographic Analysis . 79 

Addie Deposit ... 80 

Chemical Analysis 85 

P. C. E. Value 85 

Petrographic Analysis 86 

Cane Creek Deposit 87 

Chemical Analysis 89 

P. C. E. Value 90 

Petrographic Analysis 90 

Webster Deposit 91 

Chemical Analysis 94 

P. C. E. Value 95 

Petrographic Analysis 95 

P. C. E. Value 97 

Other Deposits in Webster-Balsam Area 97 

Ellijay Area .... 98 

Moons Knob Deposit 98 

Chemical Analysis 99 

P. C. E. Value- 99 

Ellijay Creek 100 



of North Carolina and Georgia 5 

CONTENTS (CONTINUED) 

Page 

Description of Areas and Deposits — Continued : 

Deposit Number Nine . 100 

Chemical Analysis 102 

P. C. E. Value 102 

Petrographic Analysis - 102 

Corundum Hill Deposit 104 

Chemical Analysis 105 

P. C. E. Value 105 

Petrographic Analysis . 105 

Norton Deposit 106 

Chemical Analysis 106 

P. C. E. Value 106 

Petrographic Analysis . 107 

Other Deposits in Ellijay Area. 107 

Buck Creek-Shooting Creek Area 107 

Buck Creek Deposit 108 

Chemical Analysis 110 

P. C. E. Value 110 

Petrographic Analysis _ 110 

Burton Lake Area „ 112 

Burton Lake Deposit 112 

Chemical Analysis 113 

P. C. E. Value 113 

Petrographic Analysis _ 113 

Laurel Creek Area 113 

Laurel Creek Deposit 114 

Chemical Analysis 116 

Petrographic Analysis . 116 

P. C. E. Value 116 

Other Deposits in Laurel Creek Area 1 1(5 



ILLUSTRATIONS 
Plate Page 

1. Forsterite olivine showing chromite — Balsam 

Gap, X. C 12 

2. Domestic basic refractories 

Principal Bources and consuming centers 16 

Olivine bell in relation to major transportation 

routes 18 

1. Fig. A — Specimen of coarse-textured dunite 

Fig. B — Specimen of coarse-textured saxonite 25 

•">. Fig. A — Specimen of fine-grained dunite 

Fig. B — Specimen of fine-grained saxonite 27 

6. Micrographs of thin sections of dunite showing 

alteration 33 

7. Fig. A — Fine-grained dunite 
Fig. B — Tough dunite 

Fig. C — Serpentinized dunite 

Fig. D — Altered dunite 35 

8. Map showing distribution of olivine in Tennessee 

Valley area 39 

9. Map showing principal olivine deposits in Ten- 

nessee Valley area 41 

10. Views of olivine outcrops 44 

11. Geologic map of Frank deposit 45 

12. Geologic map of Day Book deposit 50 

13. View of olivine quarry 51 

14. Geologic map of Newdale deposit 54 

15. Views showing geologic structures in dunite 56 



of North Carolina and Georgia 7 

ILLUSTRATIONS (CONTINUED) 

Plate Page 

16. Geologic map of Holcombe Branch deposit 59 

17. Fig. A — Large pegmatite in dunite 

Fig. B — Joints in dunite 62 

18. Geologic map of Newfound Gap deposit 66 

19. Geologic map of Balsam Gap deposit 68 

20. Typical olivine outcrop 69 

21. Views of small olivine quarries ... 72 

22. Geologic map of Dark Ridge deposit 76 

23. Views of crude olivine blocks used in furnaces 77 

24. Geologic map of Addie deposit 81 

25. Geologic map of Cane Creek deposit 88 

26. Geologic map of Webster deposit 92 

27. Geologic map of Number Nine deposit 101 

28. Geologic map of Corundum Hill deposit 103 

29. Geologic map of Buck Creek deposit 109 

30. Geologic map of Laurel Creek deposit 115 

31. Olivine loaded in railway cars 117 



LETTER OF TRANSMITTAL 



Raleigh, North Carolina 
November 12, 1941 

To His Excellency, Box. J. Melville Broughton, 
Govi rnor of North Carolina. 

Sir: I have the honor to submit herewith, as Bulletin 
No. 41, a report on "FORSTERITE OLIVINE DE- 
POSITS OF NORTH CAROLINA AND GEORGIA." 
This bullet in is being published in cooperation with the 
Tennessee Valley Authority. 

To meet the demands for defense purposes, large 
quantities of light metals are needed. Since olivine con- 
tains a high percentage of magnesium, it is hoped that 
this report, which shows huge deposits of olivine in North 
Carolina, will point out a practicable source of this metal 
for National Defense purposes. 

Respectfully submitted, 

R. Bruce Etheridge, 
Director. 



PREFACE 

This report entitled "Forsterite Olivine Deposits of 
North Carolina and Georgia" has been prepared espe- 
cially to furnish data on the occurrence, amount, mineral 
associations and chemical quality of the olivine deposits 
of the areas. The field work was done and the report 
written by Charles E. Hunter, Associate Geologist, under 
the direction of H. S. Rankin, Senior Mining Engineer, 
of the Regional Products Research Division of the Com- 
merce Department, Tennessee Valley Authority. 

The purpose of this joint publication with the Ten- 
nessee Valley Authority is to present data that demon- 
strate the presence of large reserves of olivine in western 
North Carolina and northern Georgia suitable for the 
production of special refractories and magnesium com- 
pounds. The presence of large deposits of olivine adja- 
cent to good transportation facilities in a region where 
the production of electric power is constantly increasing 
suggests splendid opportunities for the establishment of 
industries based on the utilization of these resources. 

Jasper L. Stuckey, 
State Geologist. 



FORSTERITE OLIVINE DEPOSITS OF NORTH 
CAROLINA AND GEORGIA 



By Charles E. Hunter* 
Under the direction of H. S. Rankin^ 

SUMMARY 

It is not well known that there occurs in the Southeast 
a reserve of at least 230,000,000 tons of high-grade 
forsterite olivine,' averaging 48.07 per cent of magnesia, 
suitable for the production of special refractories and 
various magnesium compounds. These deposits, because 
of their occurrence at accessible points and the fact that 
they contain more magnesium than any other common 
mineral, have excellent possibilities of being utilized in 
the development of new T important industries in the 
South. 

More than 275 peridotite 2 formations, many of which 
are dunites, 3 occur in North Carolina and Georgia. These 
deposits are coexistent with the Blue Ridge Mountains, 
and outcrop in a belt about 300 miles long. Most of 
these deposits have been examined during various recon- 
naissance surveys on associated minerals such as corun- 
dum, chromite, nickel, and vermiculite. It was found 
that a great number of these deposits are in advance 
stages of serpentinization and steatitization. 1 However, 
there are about 25 large forsterite olivine deposits, 
remarkably sound and free from alteration minerals, 
occurring in a belt 175 miles long and 15 miles wide, ex- 



: Associatr Geologist, Regional Products Research Division, Commerce Department, 
I ennessee \ alley Authority. 

* Senior Mining Engineer, Regional Products Research Division, Commerce Depart- 
ment, Tennessee Vallej Authority. 

1 Forsterite olivine — A mineral composed mostly of magnesium ortho-silicat( 

-Peridotite Dark uteen igneous rock of deep seated origin which consists wholly of 
ferromagnesian mm era Is. 

:i Dnnite —A variety ot peridotite composed mostly of olivine. 

'Serpentinization and Steatitization 1 ypes ol alteration or "decay" common to the 
peridotite class ot rocks. 



12 



FORS I ERITE I ILIVINE I DEPOSITS 




% Mwti 




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TORiTEBlTt OLIVINE SHOWING CHROMI1 E BALSAM. N C 



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A 3 a 4 A ■■ ' •■••A ■'• "■■ - A - ■ • A ■■■ •■■■A - 



l 



Plate 1 



tending from Watauga County, North Carolina, south- 
westward to White County, Georgia. Asheville, North 
Carolina, is about in the center of this belt. 

Twenty of the best, largest and most accessible of 
these forsterite olivine deposits were carefully mapped 
and sampled. Several known deposits of good olivine 



of North Carolina and Georgia 13 

were not mapped and sampled in this belt, because of 
their occurrence at inaccessible points in mountainous 
areas, which makes them of little economic value for the 
production of olivine in the near future. However, they 
constitute reserves and will be important as sources of 
olivine when access roads make them economically 
available. 

The deposits mapped consist of dunites and saxonites' 
containing from 60 to 95 per cent coarse-grained friable 
olivine. The central core, usually about half of the 
deposit, consists of relatively unaltered olivine; and the 
outer border of the formation and some faulted zones 
through the central part are composed of dunite or 
saxonite partially altered to serpentine and talc. The 
central or generally unaltered part of the deposits aver- 
age about 48.07 per cent magnesia and the outer rim, 
or faulted zone part of the formation ranges between 
40 and 48 per cent magnesia. These North Carolina 
and Georgia forsterite olivine deposits are tremendous 
in size (one contains 16,550,000 tons of sound olivine and 
24,500,000 tons of partly serpentinized dunite; the 
largest contains over 300,000,000 tons of dunite) and 
remarkably uniform in mineral and chemical compo- 
sition. A petrographic analysis of a typical sample is 
as follows: 85 per cent olivine, 10 per cent talc and 
serpentine, and 5 per cent chromite and others. A 
chemical analysis of a typical sample is shown in the 
following tabulation : 



MgO 


Si0 2 


Fe,(), 


\1. Ti, Cr Oxides 


CaO 


T T 
[gn. loss 


Total 


48.07 


40.47 


8.68 


1.21 


0. Id 


1.21 


«)<).74 



Note that in the above table the magnesia is 48.07 per 
cent and the silica is 40.47 per cent and the absence of 
large quantities of fluxing ingredients which predisposes 

•' Saxonite — A variety "I peridotite similar to dunite bui containing crystals ol i nstatiti 
usually bronzite. 



1 I FORSTER] IK < >l.l\ INE DePOSII 

its suitability as a natural refractory in block form or 
for the production of special refractories. The iron con- 
tent is 8.68 per cent which makes the fayalite content of 
the olivine less than 1 1 per cent as part of the iron is in 
the chromite. 

These deposits are well suited for the quarrying of 
high-grade olivine, since most of them, being more 
resistant to erosion than the surrounding area, stand up 
as hills of relatively sound formation. All of the twenty 
large deposits mapped in this survey are accessible to 
rail or truck transportation. Dark Ridge, Addie and 
Webster, among the largest and best deposits, are crossed 
by branches of the Southern Railway. The Day Book 
and Xewdale deposits occur less than five miles from 
Clinchfield (C.C.&O.) railroad stations. The material 
occurring in the North Carolina and Georgia forsterite 
olivine deposits is of such uniform character that, if 
occasion should arise, it could be used in a centrally 
located plant. Based upon carefully made calculations 
it is estimated that there occur within the area 1,000,- 
000,000 tons of dunite containing more than 40 per cent 
magnesia and 230,000,000 tons of "quarrable" high- 
grade olivine averaging 48.07 per cent magnesia. It is 
estimated that it will cost $0.60 to $1.50 per ton to 
quarry, crush, and screen this material depending upon 
the size ranges of aggregate desired. 

INTRODUCTION 

Olivine, one of the major undeveloped mineral re- 
sources of the Southeast, occurring in North Carolina 
and Georgia, was known as early as 1875 and described 
as "chrysolytic sandstone.'"'' Later, the olivine deposits 
were recognized as dunites and described as such by 
Pratt and Lewis in their report, "Corundum and the 
Peridotites of Western North Carolina." 7 The mineral 



1 W. C. Kerr, St. it. Geologist of North Carolina, Report, Geologic Survey of North 

Carolina, V No 1 -b"-'i p 129 
7 Joseph Hyde I'r.itr and Joseph Volney Lewis, "Corundum and the Peridotites of 

Western North Carolina," North Carolina Geological Survey, Vol. I (1905). 



of North Carolina and Georgia 15 

olivine is a common constituent of igneous rocks, which 
originate from deep within the earth. The mineral, 
usually olive green or pale yellow in color (hence its 
name), often occurs in small irregularly outlined crys- 
tals, and, more often, in grains similar in size and shape 
to those of granulated sugar. It is a magnesium iron 
orthosilicate. s The North Carolina and Georgia variety 
contains detectable amounts of nickel and chromium. An 
important characteristic of the mineral is that it contains 
75 to 95 per cent forsterite (pure magnesium silicate), 
which is a superior basic refractory 11 with a melting point 
of 1890° C. The best grades contain about 30 per cent 
magnesium, more than any other magnesium-bearing 
mineral occurring in such large quantities. 

In 1933 the experimental use of a small amount of 
North Carolina olivine as a basic refractory in the 
eastern steel industry created some interest in these 
deposits. The increase in production has been slight, 
largely because of the difficulty of obtaining satisfactory 
shapes for refractory work. Most of the consumption 
has been in the form of quarry-mined blocks. The 
present annual output from the TVA region is below 
10,000 tons, which until recently was used entirely for 
refractory purposes. Some olivine is now being used in 
experimental production of magnesium sulphate. 

These olivine deposits constitute a practically in- 
exhaustible reserve of a mineral uniform in composition. 
It was determined from the survey just completed that 
there is available from 20 readily accessible deposits 
230,000,000 tons of unaltered olivine, containing more 
than 45 per cent magnesia,"' and one billion tons of 
partially serpentinized clunite" composed of 50 per cent 
or more olivine averaging about 44 per cent magnesia. 



Magnesium-iron orthosilicate 2 (Mg.Fe) O.SiO 

9 Basic refractory --material with high resistance to heat and certain types "I sLil;. 
111 Magnesia niamiesium oxide. 
" Serpentinized dunite roclt composed principally of olivim . part ol thi olivim shows 

sifjns of alteration or "decay." 



16 



Fors ii Ri ii i n i\ ink Deposits 






•• . 



• 



t 




W 
H 
< 



OF North Carolina and Georgia 17 

Only those reserves containing more than 40 per cent 
magnesia were considered in these estimates. The re- 
serves considered are only those occurring above the 
local drainage level. Careful sampling and analyses 
show great uniformity of magnesium and iron content 
throughout the area. 

The location of these deposits within 500 miles (see 
Plate 2 and Plate 3 ) of important metallurgical centers 
favors the possibility of their development in the near 
future for the production of superior basic refractories. 
In addition, these olivine deposits are surrounded by such 
hydroelectric developments as Tennessee Valley Author- 
ity, Nantahala Power Co. (Aluminum Co. of America), 
Carolina Power & Light Co., and Duke Power Co. These 
companies can furnish low-cost electricity for processing 
the olivine into forsterite 1 - and other refractories, into 
magnesium compounds, and last, but probably most im- 
portant, into metallic magnesium. 

The potential importance of these olivine deposits in 
the Tennessee Valley region has not perhaps been fully 
realized. During times of war or national preparedness, 
the steel industry runs at capacity. One of the important 
problems in steel production is the supply of satisfactory 
basic refractory furnace linings. Magnesite," exten- 
sively used in the eastern and southern steel industries, 
is obtained either by importation or from the Pacific 
Coast states. In war times the supply of imported 
magnesite cannot be relied upon, and the domest it- 
material has to be transported from the West Coast (see 
Plate 2) . These large reserves of olivine, a basic refrac- 
tory material occurring so near the steel plants, may be 
of great importance in the national defense. 

The increased demand for magnesium in airplane 
construction, general light-weight metallic uses, military 
flares, and incendiary bombs requires that magnesium 

12 Forsti -lite .in important refractory magnesium silicate mineral. 
1:1 Magnesite The mineral magnesium carbonate (MgCOj). 



L8 



FORSTERITE < M.l\ INK DEPOSITS 



production in the United States be greatly expanded. 
Olivine, because of its tremendous, low -cost reserves, and 
high magnesium content, offers .ureal potentialities as an 
<>re of the metal. Active research, by the Tennessee 
Valley Authority, is now under way to develop a process 
for utilizing the olivine as an ore of magnesium. 




Plate 3 



HISTORY OF DEVELOPMENT 

Olivine and forsterite refractories were first com- 
mercially used in America during 1933. 14 Since that 

14 Fred A. Harvey and Raymond E. Birch, "Olivine and Forsterite Refractories in 
America."' Industrial and Engineering Chemistry, January. 1958, p. 28. 



of North Carolina and Georgia 19 

date the amount produced has increased slowly, with 
most of the use confined to experimental purposes. The 
forms in which it has been used are shaped crude olivine 
blocks, crushed bonded crude olivine, and forsterite pro- 
duced from olivine, none of which have been said to be 
entirely satisfactory industrially. 

REVIEW OF RESEARCH 

One of the earliest technical reports issued on olivine 
in the United States was by Heindl and Pendergast. 1 " 
Part of their summary states: "The results indicated 
that the material from North Carolina was sufficiently 
refractory to heat [and sufficiently resistant to some 
types of slag] to warrant its use as a special refractory. 
Bricks were easily made from run-of-mine material and 
proved satisfactory in the few physical tests to which 
they were subjected." 

"The Production of Unfired and Fired Forsterite Re- 
fractories From North Carolina Dunites," by Greaves- 
Walker and Stone, reviews previous publications on 
olivine refractories by others, and presents additional 
data obtained by them at the North Carolina Engineering 
Experiment Station. 10 

Harvey and Birch have presented well the case of the 
new refractory in their article, "Olivine and Forsterite 
Refractories in America." 17 Goldschmidt, one of the 
pioneers in research in olivine refractories, has written 
a review on its use in Europe. 1 ^ 

RESEARCH IN PROGRESS 

During 1940 and 1941 the Electrotechnical Labora- 
tory at the Norris Station of the U. S. Bureau of Mines 
has worked on the development of a forsterite firebrick 

15 Olivine .is .1 Refractory, U. S. Bureau of Standards Research Paper, R P I I ; (Februan 

1934), p. 222. 
18 Bulletin No. 16 (Septembei 1938), Engineering Experimeni Station, State College, 

Raleigh, North Carolina. 
17 Industri.il and Engineering Chemistry, January 1938, p 
ls V. M. Goldschmidt, "Olivini and Forsterit* Refractories in Europe," / il and 

Engineering Chemistry, January 1938, p. ; 2 



l'ii Forsterite Olivine Deposits 

from olivine melted ill ail electric furnace. The forsterite 
produced is nearly pure and it has promise of becoming 
a remarkably high melting basic refractory of potentially 

wide application. 

The results of recent research being carried out by 
the staff of the Regional Products Research Division of 
the TV A on magnesium chloride production from olivine 
have been encouraging. This process, if the experiments 
now under way prove successful, would make olivine 
available as a low-cost ore for the production of mag- 
nesium metal since the methods for making the metal 
from the chloride are well established.'" 

PRESENT COMMERCIAL USE 

For several years, North Carolina olivine has been 
used in the construction of semisloping back walls in open 
hearth furnaces, though the greatest use has been in 
furnace repair. The firm of Gillis and Pawel (Olivine 
Products Cpn. ) of Webster, North Carolina, has recently 
established a commercial plant for making magnesium 
sulphate"" from olivine. Their process, based on several 
years' research, consists essentially of digesting crushed 
olivine in sulphuric acid, separating the iron, and crystal- 
lizing the magnesium sulphate from solution. This is 
probably the first plant using olivine as a source of 
material for the production of magnesium salts. 

FUTURE USE OF OLIVINE 

Forsterite produced from olivine has an excellent 
opportunity, because of its refractoriness and place of 
occurrence, to become an important factor in the basic 
and special refractory industries of the country. In 
addition, the use of forsterite lining in cement kilns offers 



\ summary ol research on magnesium From olivine was presented by E. C. Houston 
;irul H. S. Rankin .is .1 paper entitled "Olivine as a Source of Magnesium," delivered 
.it ,i meeting <>t the Industrial Minerals Division of the American Institute ot Mining 
\ Metallurgical Engineers, held at Rolla, Mo. on October 24, 1941. 
Magnesium sulphate — used in rayon, textile, and tanning industries, southern bright 
leaf tobacco fertilizer, and pharmaceuticals. 



of North Carolina and Georgia 21 

great promise because of its long life and other desirable 
properties. 

Olivine, because of its high magnesium content and 
low cost, offers possibilities for the production of various 
magnesium compounds, the metal, and special fertilizers. 

ACKNOWLEDGMENTS AND FIELD WORK 

This report presents data obtained in an economic 
geological field survey by Charles E. Hunter, Samuel D. 
Broadhurst, and Gilbert C. Robinson between July 1 and 
September 15, 1940. The maps used in the report were 
prepared by Samuel D. Broadhurst. 

Acknowledgment for constructive criticism and help- 
ful suggestions in preparing this report is made to : Dr. 
Frank L. Hess, Principal Mineralogist, U. S. Bureau of 
Mines, Eastern Experiment Station, College Park, Mary- 
land; Dr. Jasper L. Stuckey, State Geologist, Raleigh, 
North Carolina; Dr. Hewitt Wilson, Supervising Engi- 
neer, Electrotechnical Laboratory, U. S. Bureau of 
Mines, Norris, Tennessee; and Dr. Geoffrey W. Crick- 
may, Professor of Geology, University of Georgia. 

REGIONAL GEOLOGY 

The western part of North Carolina and northern 
Georgia in which the olivine deposits occur is a part of 
the great belt of crystalline rocks that is co-extensive 
with the Appalachian Mountain system. This area con- 
tains such peaks as Mount Mitchell with an elevation of 
6,684 feet. The mountains in the area, for the most part, 
were formed by differential weathering; therefore the 
individual spurs and tops do not have a definite pattern. 
However, the trend of the ranges as a whole is southwest- 
northeast. 

Pratt and Lewis have made a rather thorough and 
detailed study of the geology of western North Carolina 
and little can be added in a general way to their excellent 
description of the geology of the area. So liberty is here 



22 Pons 1 1 Ri 1 1 i >i.i\ i.\i-: Deposits 

taken in quote parts of their publication, "Corundum and 
Peridotites of Western North Carolina." 21 

()n accounl of their complex structure, and highly 6rystal- 
line character, these rocks [of Western X. ('.] arc generally 

msidered to be Archean Age. . . . The principal constit- 
uent of the system is banded gneiss, which includes many 
masses of granil ic and di her disl inctly igneous rocks [diorite 
and hornblende schist] and which often, through higher 
development of lamination, passes into mica-schist and 
amphibole-schists. 

The gneisses have been usually considered, in part, sedi- 
mentary rocks that have lost their original characteristics 
(with the possible exception of bedding in some cases) in 
the great earth movements and other metamorphosing 
agencies to which they have been subjected. Some of them 
are undoubtedly granites, diorites and other igneous rocks 
that have been sheared or squeezed by some agencies, and 
transitions from the massive to the laminated forms have 
often been observed. 

Lamination is often developed where no such original 
structure existed, as in the sheared massive rocks referred 
to above. It is know that such structure produced by move- 
ment in the mass of rock may, and often does, obliterate 
whatever original structure may have been present; so that 
a sedimentary rock thus mechanically laminated and at the 
same time thoroughly crystallized would no longer show its 
original stratification. The new structural planes may in 
certain cases correspond with bedding, but often they do 
not; and it is frequently impossible even to distinguish be- 
tween gneisses and schists of igneous origin and those pro- 
duced by the extreme metamorphism of sedimentary beds. 
The strikes and dips observed in this region are in all cases 
those of secondary lamination planes, and have no reference 
to stratification nor to any particular theory of origin. 

In some regions the gneisses present several characters 
that point strongly to a sedimentary origin. They contain 
limestones in considerable amount at the forks of Caney 
Fork of Tuckaseegee River, in Jackson County, and on the 
eastern slopes of Onion Mountain and the headwaters of 
Ellijay Creek, in Macon County. These limestones are often 



1 North Carolina Geological Survey; Vol. 1 (1905), p. 24. 



of North Carolina and Georgia 23 

more or less graphitic. There are also frequent streaks and 
disseminated scales of graphite in the mica-schists . . . 
these, together with the extremely variable character of the 
gneisses in many regions and their frequent rapid passing 
into mica-schist and sometimes into quartz-schist, would 
seem to justify the reference of a large part of the series 
to a sedimentary origin. 

In recent years the theory of sedimentary origin for 
part oi the gneisses and schists has been strengthened by 
the finding of additional interbedded limestones and in- 
tern ngering quartzites with the gneisses and schists, 
such as the occurrences in the vicinity of Lake Toxaway, 
Bandana and Marshall, North Carolina, and Hollywood, 
Georgia. 

The prevailing strike of the lamination planes in the 
gneiss of western North Carolina is about N. 30 deg. E, and 
the prevailing dip is at a high angle toward the southeast. 
Very frequently local variations occur, especially in the dip, 
and the prevailing southeasterly dip will become vertical 
within an outcrop covering only a few feet and, tipping 
over, will pass into a northwesterly dip. All stages occur 
from these local variations in the dip and strike to the most 
complex gnarled and contorted forms. In general, the lami- 
nation has suffered most deformation in the immediate 
vicinity of igneous intrusions and the forces that produced 
the contortions doubtless formed simultaneously the fissures 
into which the massive rocks were injected. 

This gneissic belt of the mountain region, which averages 
about 35 miles wide, is bordered on the West and East by 
two belts of partially metamorphosed sedimentary rocks 
that are considered by Mr. Arthur Keith, of U. S. Geological 
Survey, to be of lower Cambrian Age. . . . This formation 
consists of a lower series of sandstones and conglomerates 
and an upper series of shales and limestones, the whole lying 
imcomformably on the gneisses. 

This belt of gneiss above described is cut by a great many 
narrow strips and small lenticular masses of basic mag- 
nesium rocks, chiefly peridotites, which rarely exceed a mile 
or two in length. As far as has been observed, these rocks 
are nowhere intimately associated with igneous rocks of the 
granitic type. . . . These basic magnesium rocks of North 



2 I FORSTERITE < »l.l\ INK DEPOSITS 

Carolina [and Georgia] intersecl no formations <>f later a^e 
than the supposedly pre-Cambrian gneisses. 

The peridotitea and related rocks form disconnected 
masses arranged in a line or series of parallel lines that 
coincide approximately in direction with the strike of the 
gneissic laminat ion. They almosl invariably have a sheath 
of some schistose ' mineral developed aloiitf their borders, so 
that there is rarely an absolute contact between [them and] 
the normal gneiss. 

The North Carolina and Georgia peridotites are in- 
truded into the central part of a great geanticline-"' and 
many of these intrusions are thought to have been a part 
of a volcanic system once active in pre-Cambrian times. 
Some of the dunites and saxonites (defined on following 
page ) now exposed may be part of an ancient deep seated 
volcanic system. These formations vary in extent of 
surface outcrop, from 1500 square feet (Otto deposit in 
Macon County, N. C), to one-half square mile (Buck 
Creek Deposit, Clay County, N. C. )• All the deposits 
extent downward several hundred feet, and the largest 
probably extend downward to great depths. 

GEOLOGY OF PERIDOTITES 

DUNITES AND SAXONITES 

The western North Carolina and northern Georgia 
olivine deposits can be classified as dunites and saxonites. 
The dunites are composed of essentially pure olivine with 
accessory primary minerals such as chromite or picotite, 20 
while the saxonites are practically the same except that 
they contain primary bronzite- 7 (see Plates 4 and 5). In 
many eases the bronzite has been altered to talc. The 
dunite bodies are more numerous and usually larger than 



ambrian a very early and old geologic age. 
( iii' issic lamination light-and dark-colored minerals arranged in bands in the rock. 
1 Schistosi scaly minerals such .is vermiculite or mica — forming a platy surface cross 
ion. 
1 I inticline — a told ot great magnitude (mon than 10 miles in diameter) in the rocks 

■ in eai th's outer crusr zone. 
Picotite- a chrome spinel mineral, chiefly chromium oxide. 
r ' Bronzite — Iron-bearing variety of the mineral enstatite with a bronze luster. 



Plate 4 




■ 



»*v 



h 






*' 



'" >-" 



A. COARSE TEXTURED DUNITE 
Dunite consisting essentially of unaltered, dark green olivine crystals which average about 
1 nun. in diameter. .Minute crystals of primary chromite are disseminated throughout the 
dunite. Natural size. 






£ 



r • 



*#**■" 



* * ■ 

*. i 




9 



'UK 





ft* 



.. 



IJ. COARSE TEXTURED SAXONITE 

Saxonite composed oi partlj altered, dark green i llvine, bronzlte, and chr Ite The olivine 

crystals average about I hum. in diameter and usually show shattering due to serpentlnlzatlon 
around the borders The bronzlte crystals are parti] altered to talc. Natural size, 



26 Forsterite Olivine Deposits 

the saxonites, which frequently arc found in contact with, 
or surrounded by, dunite. 

( olivine deposits now exposed at the surface by erosion 

were probably formed (crystallized and cooled) at a 
depth greater than ten miles below the surface at the 

time of their injection. This depth of intrusions is sub- 
stantiated by the structure of the region, and the fact 
that erosion during geological times has removed rocks 
and sediments from the area totaling approximately ten 
miles in thickness. Grout states that ultra-basic igneous 
rocks, such as dunites, are deep-seated in formation. 28 

The country rock, surrounding these intrusions, is in 
most instances hornblende"" gneisses and schists. A 
direct relationship between the hornblende and peridotite 
formations is evidenced by the fact that olivine grains 
have been found in some hornblende formations adjacent 
to the dunites. Such a relationship was observed in 
Yancey and Clay Counties, and suggests that the two 
basic igneous formations probably originated from the 
same parent magma occurring at a much greater depth. 
The peridotites (olivine-bearing rock) are apparently 
tlie younger of the two, because in many places, Webster 
for example, large and small hornblende inclusions were 
noted surrounded by dunite. The contact between the 
inclusions and the dunite is seldom sharp, because a 
fringe of impure vermiculite and actinolite occurs around 
the hornblende inclusion which indicates the meta- 
morphic action of the peridotite intrusion. 

The peridotites with which this report is concerned 
are of the dunite and saxonite type consisting of more 
than 60 per cent olivine. These intrusions can be sub- 
divided into two structural types, the most common of 
which is a lens-shaped intrusion with the long axis 



■ Frank I < Irout, "Petrography and Petrology" (New York: McGraw-Hill Book Com- 
pany, Inc.. 1932) p. 147. 

19 Hornblende — a complex black mineral composed mainly of magnesium, calcium, 
aluminum, and iron silicate. 



of North Carolina and Georgia 



27 



parallel to the regional schistosity, and the other is of the 
ring-dike or crescent type. Similar olivine occurs in both 
types, but the internal structural features are somewhat 



Plate 5 








A. FINE GRAINED DUNITE 
This dunite consists essentially of unaltered, light green olivine and 
disseminated minute crystals of primary chromite. The olivine grains average 
about 0.2 mm. in diameter. Natural size. 



'"' 




' • K. .-#* 






*'0 ' 



M 






B. PINE GRAINED SAXONITE 
A partly altered saxonite consisting of light green olivine, chromite, 
bronzite, and talc. The olivine grains average less than 0.2 nun. iii diameter, 
and the bronzite crystals average more than l 11 nun in diameter, Some of 
the bronzite is entirely altered to talc. The specimen shows a slight amount 
of chloritization. Natural size, 



28 FORSTERITE OLIVINK DEPOSITS 

different In the lens-shaped type the cooling joints and 
occasional faults arc the most prominent features. In 
the ring-dike type, the most noticeable feature is the 
parallel lamination which on a weathered surface has the 
appearance of thin-bedded sandstone. In all cases this 
lamination, is roughly parallel to the contact of the olivine 
formation and to the schistosity of the country rock. 

Segregations of various types of olivine are more 
pronounced in the ring-dike than in the lens-shaped for- 
mations. This difference is probably due to later basic 
intrusions which have undergone little alteration, and to 
structural features which have protected certain areas 
from hvdro-thermal solutions. 

ASSOCIATED MINERALS 

The dunites and saxonites contain accessory minerals 
such as chromite, picotite, bronzite, and many others/ 
Olivine accounts usually for more than 60 per cent of the 
formation and most of it consists of 80 per cent forsterite, 
11 per cent or less fayalite,'" and the remaining 9 per 
cent or less of other magnesium minerals.' 1 " In some of 
these deposits chromite is a conspicuous mineral occur- 
ring as well-formed disseminated crystals throughout the 
dunite rock, or as small lenses and veins of massive 
chromite surrounded by friable and granular olivine. At 
some places, such as a part of the Webster ring-dike 33 
series, the chromite makes up as much as 25 per cent of 
the dunite." The secondary magnesium minerals de- 
rived from olivine include a wide variety of hydrated 
minerals. 35 

At a few places, especially near Webster and Demo- 
crat, N. C, nickel silicate veins, nickeliferous clay, and 



30 Pratt and Lewis, op. cit., p. 29. 

I ayalite an iron silicate mineral. 
" 2 R. A. Heinill and W. L. Pendergast. "Olivine as a Refractory," U. S. Bureau of 

Standards Research Paper 645, (February 1 ( ^34), p. 219. 
33 Ring-dike — a geologic structure circular or elliptical in shape. 
1 Edwin C. Eckel, Charles E. Hunter, and Philip W. Mattocks, "Iron, Chromite, and 

Nickel Resources of the Tennessee Valley Region," Tennessee Valley Authority, 

Geologic Division, Bulletin 10 (193S) p. 19.' 
35 Pratt and Lewis, op. cit., pp. 74 and 112. 



of North Carolina and Georgia 29 

nickel-bearing vermiculite are rather conspicuous in the 
dunite. 36 These veins seldom exceed two feet in width 
but sometimes they are found rather closely spaced ; that 
is, occurring only a few feet apart and separated by 
dunite, which is cut by many tiny veinlets of a harder 
nickel silicate mineral, genthite. In the Webster area 
the nickeliferous veins are reported to average about 
5.34 per cent NiO, and the altered dunite and serpentine 
associated with these veins to average about 1.50 per cent 
NiO. :<T Some nickel is detectable in all the olivine deposits 
and many of them average more than 0.25 per cent nickel. 
Vermiculite occurs with all the dunite formations both 
as fringe veins in contact with the country rock and as 
interior veins in joints and faults within the olivine 
body. :!s These veins vary in thickness up to 15 feet, the 
average being about three feet. Corundum is a common 
accessory mineral. In the Ellijay area of Macon County, 
N. C, vermiculite occurs rather abundantly with the 
olivine-bearing formations. However, it is usually found 
in commercial quantities only in those formations 
through which pegmatite 39 solutions (hot silica-bearing) 
have passed. Many of the dunite bodies offered struc- 
tural weaknesses ideal for the entering of intrusions and, 
therefore, contain numerous small pegmatites with 
highly altered dunite on each side. 

Many of the dunites contain veins and seamlets of 
anthophyllite asbestos. The olivine associated with this 
asbestos is usually of an inferior quality because of the 
occurrence of a high percentage of chlorite and talc, 
developed along with the anthophyllite, which lowers the 
magnesium content and refractoriness. In addition, the 



30 Eckel, Hunter, and Mattocks, op. cit., p. 22. 

37 G. W. Pawel, "Nickel in North Carolina," Engineering and Mining Journal, Octobei 

1939, p. 35. 
■'"Charles E. Hunter, Philip W. Mattocks, and Others, "Vermiculite and Bentonite of 

Tennessee Valley Region," Tennessee Valley Authority, Geologic Division; Bulletin 5 

(1936) p. 3. 
3il Pegmatite — an igneous intrusion composed ol solutions carrying acid minerals such as 

quartz and feldspar. 



30 FORSTERIl i: < »i.i\ INE DEPOSITS 

exteriors of individual olivine grains are partly altered 
to secondary magnesium minerals which, in most cases 
are inert to acids; consequently the material is rendered 
undesirable Tor use as a source of magnesium in a 

chemical process. 

These associated minerals offer possibilities as im- 
portant by-products in any substantial olivine produc- 
tion. Such minerals as vermiculite, talc, asbestos, 
chlorite, chalcedony, corundum and some chromite and 
nickel ore could he produced at the quarry along with the 
olivine. However, much chromium and nickel would be 
obtained from the residue and solution after the mag- 
nesium has been taken out of the olivine by a chemical 
process. 

SERPENTINIZATION 

The olivine from most of the deposits shows some de- 
cree of serpentinization under the microscope and in 
some cases the serpentinization has been so complete that 
it is difficult to find remaining a remnant or skeleton 
olivine crystal. A widespread misconception is the belief 
that the serpentinization in the dunite and saxonite is a 
surface phenomenon due to weathering. This conception 
is not substantiated by field evidence. Pratt and Lewis 
recognized that the serpentinization was due to hydro- 
thermal action which took place on the olivine many 
millions of years before the deposits were exposed by 
erosion. They presented thorough and convincing data 
on deep-seated serpentinization of the North Carolina 
dunites in their excellent report, "Corundum and Perido- 
tites of Western North Carolina." Pratt and Lewis state: 
"Serpentinization, therefore, is believed to be a process 
that can take place only below the depth of active 
weathering .... On this hypothesis serpentine could 
exist at the surface onlv where a certain amount of 
overlying rock has been decomposed and removed after 
the alteration of the peridotite [dunite] into serpen- 



of North Carolina and Georgia 31 

tine." 4 " G. W. Bain recently reviewed previous papers 
on serpentinization and presented additional data of his 
own. Part of his paper is here quoted." 

These important contributions to the literature on origin 
of serpentine indicates four modern schools of thought. 
First, Benson, Arshinov and Merenkov, and Hess would in- 
voke the process of autometamorphism — alteration by a 
late stage portion of the ultrabasic magma while it is in the 
process of crystallization. Second, Graham and Dresser 
would attribute the change to attack of a granitic differen- 
tiation extract of the original ultrabasic, after crystalliza- 
tion of the olivine. Third, Cairnes and Cooke would inter- 
pose a period of tectonic movement between crystallization 
of the ultrabasic and serpentinization, but they refrain 
from ascribing an origin to the solutions causing the change. 
Fourth, Foslie and Du Rietz seemingly concur with Cairnes 
and Cooke but deny any relationship between the original 
ultrabasic magma and the solutions causing the change. 
Bain observed that fault-sheared zones were com- 
pletely serpentinized while the bordering less disturbed 
saxonite was only slightly serpentinized. He is of the 
opinion that much of the serpentinization (in Vermont) 
is due to solutions originating from without the for- 
mation. 4 " 

No one mode of serpentinization was solely respon- 
sible for the serpentine developed in the dunite and 
saxonite occurring in North Carolina and Georgia. Field 
evidence shows that a combination of the serpentinization 
processes was active in these deposits. Alteration by 
autometamorphism and later by granitic or pegmatitic 
intrusions are the two principal and most common typos 
of serpentinization found in these deposits. 

There is little doubt that all the olivine deposits | in 
the area covered by this report), when first formed, were 
either dunite or saxonite of a very similar and uniform 
mineralogical and chemical composition (see Plate <>). 



I fltrabasics," />.■< " I • Society 



in 


Pratt 


and Lewis. 


, up. ril. 


. P- 


119. 




41 


G. W 


. Bain, "S< 


rpentinization <>l V 


ermon 




of Ameru a, Vol. 


17 (193 


6) i 


.. L964 




42 


Ibid., 


p. 1968. 











32 Fors n srite i »i.i\ ink Deposits 

But immediately after the magma was intruded into the 
country rock, the olivine began to undergo alteration of 
the type known to geologists as bein.u, - "cooked in its own 
juices/* That is, during the cooling period of the olivine 
magma, the entire formation was subjected to the vapors 

DESCRIPTION OF PLATE 6 

Showing photomicrographs of thin sections of dunite illustrating 
various Btages of alteration of olivine 

Figure 1. Dunite from the Railroad cut (Dark Ridge De- 
posit) 2 miles west of I'.alsam Gap, Jackson County, N. C. A 
photomicrograph in ordinary tight, magnified 12 diameters. A 
typical granular dunite. showing only the slightest trace of alter- 
ation to serpentine. Thin section No. Wll. 

Figure2. Dunite from Webster. Jackson County, N. C. A 
photomicrograph in ordinary light, showing the beginning of 
serpentinization along the borders of the olivine grains. 

Figure 8. Dunite. Webster, X. C. A photomicrograph in 
ordinary light, magnified 18 diameters. Shows an advanced 
stage in the alteration of the olivine to serpentine. Some of the 
olivine grains are darkened on the borders by the segregated 
iron oxides. Thin section No. Wl. 

Figure 1. Dunite. Webster, N. C. A photomicrograph in 
ordinary light, magnified 18 diameters. Similar to Fig. 3, except 
in the larger amounts of the iron oxides segregated along the 
borders of the olivine remnants. Thin section No. W9. 

Figure 5. Dunite from Cane Creek, 5 miles northeast of 
Webster, X. C. A photomicrograph in ordinary light, magnified 
1 1 diameters. Shows the typical structure of laminated dunite, 
with alternating layers of sheared and unsheared granular 
olivine. Only a trace of serpentinization. Thin section No. 
Wl':;. 

Figure6. Dunite from 5 miles northeast of Webster, N. C, 
on the road from Webster to Hall. A photomicrograph in ordi- 
nary light, magnified 18 diameters. Shows dunite altered to 
chlorite in radiating tufts, with granules and irregular aggre- 
gates of magnetite. Small unaltered remnants of olivine are 
scattered throughout the field. Thin section No. W5a. 



Plat '- and description thereof taken from Joseph Hyde Pratt and Joseph Volney 
I ewis, "Corundum and the Peridotites of Western North Carolina," North Carolina 
Geological Survey, Vol. 1. pages 454 and 45 ; . 



Plate 6 




Fig. 






vSg 



V,. t^^'« 



%--- 



1 







' -fes#i 



fcjUNS*- 










8 I FORSTERITE ( OLIVINE DEPOSITS 

DESCRIPTH >X OF PLATE 7 

A. Pine-grained dunite made up of light green olivine with 
disseminated chromite. The olivine grains average about 
11.12 mm. in diameter and are entirely surrounded by yellow- 
ish serpentine. The chromite crystals arc well defined octa- 
hedrons averaging about <>.."> mm. in diameter and show no 
indications of being altered. Natural size. 

B. Dark gray dunite made up of interlocking olivine crystals 
which average about '2 mm. in diameter. As seen in thin 

ction, serpentine forms about 15 per cent of the rock and 
is found to penetrate the olivine crystals. Chromite is 
sparingly present, and as seen microscopically, occurs as 
remnant crystals partially replaced by chlorite. Natural 
size. 

< . A fine-grained dunite consisting of light green olivine crystal 
remnants enclosed by brown and gray serpentine which 
imparts a dark color to the rock. This dark, olive-drab 
color is characteristic of olivine that has undergone hydro- 
thermal serpentinization. Natural size. 

I). A representative specimen of medium-grained dunite con- 
sisting of pale green olivine partially altered to serpentine. 
Note the vein of secondary dolomite with small enclosed 
crystals of chromite. Natural size. 

and solutions being produced during the time of crystalli- 
zation and cooling of the intrusion. After the olivine 
bodies cooled, many of them underwent repeated periods 
of serpentinization by invading pegmatite solutions (see 
Plate 7, Fig. C ) . So it is no wonder that all conceivable 
stages of serpentinization are represented in the various 
olivine deposits in the area. In most cases, however, 
parts of the olivine formations were protected by faults 
from the solutions and have remained relatively sound 
and free from serpentine growth. This is evidenced by 
the fact that the rising solutions were confined princi- 
pally to the fault zones, and did not extend outward from 
them to any great extent into the main body of the 
deposit. 



Plate 7 






A. 



B. 



■ ■ 









i 



| H 



c. 



I). 



M - s s 

The Balsam i Dark Ridg ^ 

I in detail on pag " 
rpentin: a. H both o: thesi sits 

have undergon- morphism; tha: is, 

^lutions liberated during the -:allization 

:iod of the magma. Alteration from pegm; or 

g anitic intrusions are almost entire! ; -ent in thesr 

Thus, these :wo deposits of 

oli\*ine deposits .ich have undergone a minimum 

amount of serpentinization. The Democrat dunite 

bed in detail on page 61 is several large 

pegmatities and almost the entire formation is high 

Thus it is xample of a formation 

ich has undergone a great deal of both types of 

STLATmZATIC'' 

- ". ".- :.. -r : . ..r. . ■.:: :. . :::::: :: 
... .::. :..r • : "r". : — : iuziitrs . .:".". ?axoz:::e5. This 
" - i :-..'r ::■.'.: = _ : . :: " a::aci-:i r.z -:.: .-r us 

- /-:: r.s ■ :-h ; - :hf iur.ix ::.: :::::: ure : a". ■:•" s ap- 

■ -'.- It is later than serpentinization and is produced 

-llicec as s idution originating from without the 

This method of alteration is of little im- 

". ..- --..-.■>-.- : :> '..::/_--' -r.'.r..'. usuaiiy :\:\7.r.ri 

- - . -: -> : : -r : --.:- :. ..." :;-.rrr::re sr.iu'.n :: 
tc-zirZ'r "■":_-. :r.r ::: / .:: /. : .:' ;:.t 

Ir. discussing the origin of the dunites. Greaves- 
Walker and Stone, in their publication, 
more probable tha: the accumulated c: ystals of olivine, 
formed by sinking from a complex magma, were intruded 
into surrounding rock while in a more or less plasti 
state, in which case the temperature existing would ha - 
been reasonably low and, therefore, the eonta zie 

would be comparatively nanx 7 r : 



of N rth IB :.:.■• -.:■: .-i b ,:.-. 

:ement with : "An xamp.e : :his condition has been 
noted in the biotite schist underlying the dunite 
Balsam. X. I The - :st contains iarre an: ur.ts ■:: 
plagioclase and is not altered to a depth of more than 
t ] inches at the contact with the dunite. thei s 

made similar .statements trying to explain the absei 
:■: :outact ntetantorr.hisru. ?:: euaruyir. Hess -tates 
"The absence of contact metamorphism around basic in- 
tra.-: ns favors the hypothesis "reiatiUi : — eutiui- 
zation] that the solution- were ::: _ ..-the: from the 
country rook? in:: the :::._:::. than .r versa N 
doubt shortly after the olivine was intruded the sur- 
rounding country rock did sfa : :. :: rnetamorphism. 
However, all signs of this .:.:.: /T.amorphism have 
long since been obi: berated the schist - e eloped 

in the rocks during the several periods of great earth 
movements which the : e h a s undergone since the n : st 
olivine intrusions. Also their is deai evidence .: many 
::' the he:;:si:s that there has heeu ntneh fauit us iate- 
n:eut a.ozti the :-:uta:ts. s: it is rare :u:":eo-t that the 
dunite is now in contact wit:: the rock into which :: 
intruded. This condition is well ill:: - : : .-. :ed in the central 
western pan of the D: ? h iuu:te-sax:u:te thrntat: 

see Plate 11). Here the iuuite is in ::re:t : utact 
a large lens of the Spruce Pine Alas 
relatively recent acid ( high silica ) intrusion, and there 
-ign of serpentin ization due t: the presence of the 
alaskite. which pi ves that the dunite and alaskite 
been brought togethei :aulting. 



*h. i 

- 



FORSTERITE < M.l\ INK DEPOSITS 

WEATHERING 

The dunitea and saxonites, composed almost entirely 
• ii' forsterite olivines that have not undergone serpentini- 
ition, do not weather by decay as is customary with 
mosl rocks. Forsterite olivine is rather soluble and goes 
into solution in a manner similar to that of a pure lime- 
stone; thus the surface of an outcrop is covered by a thin 
coat of insoluble residue under which there is sound 
olivine. However, olivine formations are more resistant 
to mechanical erosion than the surrounding country rock 
and thus usually stand up as hills in a mountainous 
country where the rain fall is heavy and the erosion is 
rapid. 

DESCRIPTION OF AREAS AND DEPOSITS 

For convenience of description of deposits and group- 
ing of tonnage estimates, the olivine belt has been divided 
into eight areas. These areas have been named after 
prominent geographic points occurring within them. 
They are listed as follows: (1) Frank, (2) Toecane, 
(•*>) Canton-Democrat, (4) Webster-Balsam, (5) Ellijay, 
(6) Buck Creek-Shooting Creek, all in North Carolina, 
and (7) Burton Lake, and (8) Laurel Creek, in Georgia 
i see Plate 8). The extent of any one of the areas is not 
indicative of the quantity of olivine occurring within its 
limits. For example, No. 4 (Webster-Balsam), although 
one of the smallest in areal extent, contains more than 
twice as much olivine as any other. Also it might be 
stated that olivine from two or more areas may be drawn 
to a centrally located point for processing. For example, 
olivine produced in areas Nos. 3 and 4 (see Plates 8 and 
9 i could conveniently be processed at any one of several 
points along the main line of the Southern Railway in the 
French Broad River valley in the vicinity of Asheville. 

RESERVES OF OLIVINE 

Reserve tonnages have been calculated for each of the 
olivine deposits and totaled for each area. These calcu- 



of North Carolina and Georgia 



39 



00 

H 
H 
< 




in Fobs i eri i e < olivine Deposits 

lations arc based on carefully made geologic maps of 
each deposit. Most of the deposits were mapped in detail 
.Hi a scale of one inch equals 500 feet. On these maps 
the olivine has been divided into two classes — one, 
relatively unaltered granular olivine, and the other, 
serpentinized dunite. The areas shown on the maps as 
"relatively unaltered granular olivine" is composed 
chiefly of sound, sugary, friable olivine showing little 
indication of having been altered to other magnesium 
minerals with inferior refractory and chemical qualities. 
The olivine included in this classification contains more 
than 15 per cent MgO and has less than 2 per cent ignition 
loss. This grade of olivine usually occurs in the central 
part ol* the formation. 

The area shown on the map as "serpentinized dunite" 
is composed mainly of faulted and partly serpentinized 
dunite and saxonite and in some cases includes steatitized 
material. However, most of it consists of dark olive- 
green olivine showing some alteration to various second- 
ary magnesium minerals. Included in this classification 
is material containing at least 40 per cent magnesia 
suitable for some refractory and most chemical processes. 
This type of olivine rock usually occurs near the borders 
of the deposit. 

In most cases the topography has been shown on the 
maps by contours of 50-foot intervals. The elevations 
were determined with an aneroid barometer. The ton- 
nage calculations for each of the deposits are based only 
on the olivine and dunite occurring above the local drain- 
age level and are therefore very conservative. This is 
the material that could be produced from the deposit by 
a gravity-draining quarry. It is thought that in all 
deposits more olivine occurs below this level than has 
been included in the above calculations. Underground 
mining methods could be used on many of the deposits 
but this is not necessary because of the existence of 



of North Carolina and Georgia 



41 



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12 



FORSTERITE < >I.I\ INK DEPOSITS 



numerous excellent quarry sites having high-grade 
olivine with little or no overburden. The specific gravity 
was determined on seventy representative olivine sam- 
ples taken from the various deposits in the area. The 
average specific gravity 40 of the olivine was found to be 
3.17. From this specific gravity the olivine was calcu- 
lated to weigh about 200 pounds per cubic foot, which 
figure was used in making the tonnage estimates. 

In making the tonnage estimates, the areal extent of 
the two grades i'or each deposit was determined from the 
geologic map by use of a grid system. The volume 
determination was made separately for the area between 
each contour interval. The depth was determined by the 
local drainage condition at each deposit. The total ton- 
nage for each of the olivine areas is listed in the following 
table: 



Table. — Olivine Reserves in the Tennessee Valley Region. 



\ki \ 



Frank 

Toecani- 

Canton-Democrat.. 

fir-Balsam.... 

EUijay 



Relatively Unaltered 
( divine 

+ 45% Magnesia 
— 2% Ignition Loss 



Buck Creek-Shooting 
Creek 



Burton Lake 

Laurel Creek 
( hlit r areas (estimated) 
Total Reserves 



(tons) 
2,250,000 

4.800,000 

10,090,000 

122,690,000 

20,020,000 

60,000,000 



1,440,000 

i:. ooo, ooo 



Serpentinized Dunite 

40% to 45% Magnesia 

+ 2% Ignition Loss 



233,290,000 



(tons) 
10,550,000 

23,800,000 

69,230,000 

334,000,000 

56,340,000 

325,000,000 
25,000,000 
17,650,000 
85,000,000 



946,570,000 



Total Reserves 
Per Area 



(tons) 

12,800,000 

28,600,000 

79,320,000 

456,690,000 

76,360,000 

385,000,000 
25,000,000 
19,090,000 
97,000,000 



1,179,860,000 



M Determined by Jolly balance at TV A Minerals Testing Laboratory, Norris, Tennessee. 



of North Carolina and Georgia 43 

FRANK AREA 

The Frank area contains approximately 2,250,000 
tons of relatively unaltered granular olivine and 
10,550,000 tons of serpentinized dunite. This area is in 
the western part of Avery County, North Carolina, about 
45 miles northeast of Asheville. It extends from Plum- 
tree northward to near Cranberry, a distance of about 
nine miles, and is about five miles wide. The area lies 
within rugged mountains; the southern two-thirds is 
drained by the North Toe River and the remaining third 
by the Watauga River, both of which are part of the 
Tennessee River system. U. S. Highway No. 19E 
traverses the area lengthwise and the E.T. & W.N.C. 
narrow-gauge railroad serves the northern half of the 
area. 

Two deposits, the Frank and Senia, were mapped and 
sampled. Several other deposits occur within the area, 
but they were not mapped or sampled, because they were 
located at somewhat inaccessible places, and were there- 
fore of little importance for immediate future produc- 
tion of olivine. 

THE FRANK OLIVINE DEPOSIT 

The Frank olivine deposit occurs at Frank, N. C, 
about two miles south of Minneapolis, N. C, on a branch 
of the E.T. & W.N.C. railroad. U. S. Highway No. 19 
passes near the western and northern sides of the deposit, 
and the North Toe River flows adjacent to and across 
part of the formation. This deposit is well exposed in 
two barren hills on the south side of the river (see Plate 
10, Fig. A). The larger and westernmost hill rises 
about 300 feet above river level. The Frank deposit is 
about 1400 feet long and averages about 400 feet in 
width. 

Slip-fiber anthophyllite asbestos, which occurs in the 
contact zone of the formation and in many of the in- 
terior faults, has been produced intermittently for many 



1 1 



Forsteri i e i n.i\ ink Deposits 



Plate LO 




I 



l"i..i 1:1 A Barren outcrop of olivine showing asbestos and talc prospects. 




'•^'.i 



Kn.i 1:1 l', olivine outcrop showing thin overburden. 










Piotjki C. Outcrop of < oarse-grained olivine showing sharp edges on the 
boulders which indicate the absence of weathering. 



of North Carolina and Georgia 



45 



years from this deposit. Vermiculite and a rather pure 
foliated apple-green talc are associated with the asbestos 
and have been mined to a limited extent. 

A north-south faulted or squeezed zone near the 
middle divides the deposit into two parts (see Plate 11 ). 
The eastern part, which outcrops as a rounded barren 

Plate 11 




bCALE 



CONTOUR INTERVAL SOTEET 
DATUM MEAN SEA LEVEL 



FRANK DEPOSIT 



LEGEND 

RELATIVELY UNALTERED GRANULAR OLIVINE 

SERPENTINIZED DUNITE 
TALCY VERMICULITE FRINGE ZONE 
BIOTITE SCHIST 
Y/A HORNBLENDE GNEISS 



16 FORSTERITE < M.i\ INK DEPOSITS 

hill, contains very little overburden except for some 
residua] material between the dunite boulders. This 
part, composed mostly of coarse-grained granular olivine 
(see Plate 10, Fig. B), contains irregular areas of closely 

spaced, small chromite crystals. Hand specimens from 
the interior of the olivine boulders show little serpentini- 
zation to the unaided eye: however, near the faulted or 
squeezed zone there occur small areas that have been 
almost completely changed to serpentine, but these are 
small and closely associated with the slip-fiber asbestos. 
Several small pegmatites of no economic value outcrop 
on the northern slope of this hill. 

The western part of this formation, the larger of the 
barren hills, is composed mostly of a fine-grained granu- 
lar olivine, which consists partly of the interlocking 
crystalline variety. Here, the olivine ranges from dull 
green to light brown in color, while that on the opposite 
hill is of a darker green variety. Few accessory minerals, 
except large crystals of dark green chlorite in thin veins, 
occur with the olivine on the western hill. Overburden 
here, as well as elsewhere on the deposit, is rather thin, 
usually less than five feet. The western contact is of 
particular interest because at this point the hornblende 
schist dips at about 10 degrees to the southeast under 
the dunite, and there appears to be a rather sharp con- 
tact 1 tot ween these two basic materials, a condition which 
is indicative of a fault contact. 

The Frank deposit contains about 2,250,000 tons of 
relatively unaltered granular olivine and about 9,750,000 
tons of serpentinized dunite above river level. The 
eastern part of the deposit offers good possibilities for 
quarry sites; and, no doubt, some asbestos, talc, and 
vermiculite could be obtained from any large-scale 
operation here. 



of North Carolina and Georgia 47 

petrographic analysis "" 

Sample — Frank B-l. The principal constituents of this 
specimen are olivine (70 to 80 per cent), the fer- 
ruginous enstatite, bronzite (10 to 15 per cent), 
chlorite (about 5 per cent), chromite (less than 1 
per cent), a small amount of antigorite, and a 
few crystals of talc. 

Most of the olivine occurs as large crystals, 1 to 
2 mm. in diameter. In the areas where the 
bronzite is found the olivine crystals are much 
smaller. The olivine is fairly high in iron, indi- 
cated by iron oxide in the antigorite alterations 
along crystal boundaries. 

The chlorite was observed in several fairly large 
areas and surrounding the chromite crystals. 
Sample Frank B-l has a P.C.E. value" of +36. 

THE SENIA DEPOSIT 

The Senia deposit, a mile southwest of Frank Post 
Office, N. C, outcrops at the mouth of Roaring Creek in 
a road cut along U. S. Highway No. 19E. Thick horn- 
blende talus conceals much of the formation, but it is 
thought to be about 800 feet long and 300 feet wide. 
Olivine exposed in the road cut, about 25 feet above creek 
level, is a fine-grained granular bluish variety containing 
chlorite flakes. This deposit is estimated to contain 
800,000 tons and is suitable for only a relatively small 
quarry operation. 

Similar deposits occur to the north and east of Frank, 
N. C, but were not sampled because of their occurrence 
at points so inaccessible that they are of little value for 
immediate production. These deposits are likely to enter 



•'"' Petrographic analysis made by W. Wurth ECriegel, Department ol Ceramic Engineer- 
ing, University of North Carolina, Raleigh, North Carolina. 

■' \|| |'. c. !•,. values in tins report were determined by Gilbert C Robinson, l\ \ 
Minerals Testing Laboratory, Norris, Tennessee. P C I is abbreviation of pyro 
metric cone equivalent which is used to designate the softening or melting tempera 
tuns ol ceramic materials. P. C. E. value ol I ; <> means that the sample began to 
soften at a temperature "I 1800 degrees C. The temperature ol thi olivini cones 
were brought up to P. C. E. value of 29 at a fast rate and thereafter fired at the standard 
rate set by the American Ceramic Soeit t \ 



18 Fors ["Erite < )i.i\ ink Deposits 

into production when the demand is sufficient to justify 
the building of access mad.-. 

TOECANE AREA 

The Toecane area is characterized by fine-grained 
dunites and saxonites that have a distinctive yellow color 
dm the weathered surface. This area is estimated to con- 
tain 1,800, I tons of relatively unaltered granular 

olivine and 23,800,000 tons of serpentinized dunite and 
saxonite. 

The area is about 30 miles northeast of Asheville, 
\\ C. and extends from near the center of Yancey County 
to a short distance beyond Bakersville in Mitchell County. 
This area is about 12 miles long and 8 miles wide. The 
Toe River flows from east to west across the middle of 
the area and the Clinchfield (('.('. & O.) railroad closely 
parallels the river. The northern end is served by State 
Highway No. 19 and the southern by U. S. Highway No. 
19E, with many connecting good gravel roads. The 
whole area lies in mountainous terrain, and the entire 
drainage is into the Toe River, a part of the Tennessee 
River system. 

THE DAY BOOK DEPOSIT 

The largest and most outstanding peridotite in the 
Toecane area is the Day Book deposit occurring about 
three miles north of Burnsville, Yancey County, N. C, 
on Mine Fork of Jacks Creek two and one-half miles 
southwest of the Clinchfield (C.C. & O.) railroad station 
at ( Ireen Mountain. 

The Day Book deposit is about 2,000 feet long and 
600 feet wide, outcropping as two hills on both sides of 
Mine Fork Creek (see Plate 12). Each hill rises to about 
L75 feet above the creek level. The steep sides of the 
deposit, facing the creek, have practically no overburden. 
Veins of chromite occur in the dunite at the extreme 
southwest and northeast ends. This chromite has been 
prospected at the southern end of the formation by means 



of North Carolina and Georgia 49 

of several pits and at the northern end by means of a 
shaft more than 100 feet deep. Both of these locations 
are well above the creek level ; the chromite content, how- 
ever, is probably too low to be worked economically. 

This peridotite consists of partly altered and rela- 
tively unaltered dunite and saxonite. Much of the outer 
portion has been altered by hydrothermal solutions, while 
the relatively unaltered material occurs as a lens-shaped 
zone near the center of the formation. 

The dunite is composed of fine-grained olivine and 
small crystals of chromite (see Plate 5, Fig. A). Much 
of this material is extremely friable, and has a grain size 
of about 0.2 mm, which is smaller than that of the aver- 
age olivine. However, near the chromite concentrations, 
the olivine is quite coarse. Individual grains, ranging 
from 3 to 4 mm in diameter, were noticed near the 
chromite pits south of Mine Fork Creek. The degree of 
serpentinization in the dunite is comparatively small. 

The saxonite is composed essentially of fine-grained 
friable olivine, many bronzite crystals, and small 
amounts of chromite (see Plate 5, Fig. B). This rock 
occurs surrounding, and as fault blocks within, the 
dunite. In most cases the bronzite, often comprising 15 
per cent of the rock, has been partly or completely altered 
to talc. 

The second largest olivine quarry in North Carolina 
is located above the road in the west central part of the 
formation (see Plate 13, Fig. A). This quarry has been 
an intermittent producer of olivine for about five years. 
The olivine produced is divided into two types. Grade 1 
consists of fine-grained friable, fresh material containing 
practically no accessory minerals except chromite. This 
grade is produced almost entirely from the dunite. Grade 
2 is a fine-grained, friable olivine which contains talc 
in noticeable quantities. Most of the talc is an alteration 
product of the bronzite. Near the faults and Larger 






Kors 1 1 1:1 1 1 ( nix i\i Deposits 



I 'I VI K L2 




SCALE 



2SO 



CONTOUB INTERVAL SO FEET 
DATUM A5SUMED 



DAY BOOK DEPOSIT 



LEGEND 



fcX:l RELATIVELY UNALTERED GRANULAR OLIVINE 



SERPENTINIZED DUNITE 
I TALCY VERMICJlITE FRINGE ZONE 
LZJ BIOTITE SCHIST 
223 HORNBLENDE GNEISS 



of North Carolina and Georgia 



51 



Plate 13 




Figure A. — Olivine quarry after blast. Note vertical drill holes in quarry face 




* ' m 



'igi re I?.- -Small olivine quarry in large residual boulders of dunite. 



52 



Kors i ri;i 1 1: I m.i\ i\i I DEPOSITS 



joints in the Day Rook deposit the olivine shows signs of 
chloritization. This material is discarded when en- 
countered in quarrying. The Day Book deposit has 
excellent topography Tor two large quarries. This 

deposit is estimated to contain o,l<so,()()() tons of rela- 
tively unaltered granular olivine and 6,710,000 tons of 
serpentinized dunite above the level of Mine Fork Creek. 

CHEMICAL ANALYSIS 

Average of Five Commercial Shipments"'- 



MgO 




F« 
7.60 


MM 


CaO 


\lk. 


Ign. Loss 


Total 


W 77 


in 93 


1.32 


0.29 


0.13 


L.09 


100.13 





Fine-grained Dunite Relatively Unaltered Olivine 




Samples" 


MgO 


SiO 


Fe 2 < h 


Ti, Cr, \1, 
(Oxides) 


CaO 


lull. Loss 


Daj 


Book \-l 


1 1 n 


in 


7.66 


2.18 


0.00 


0.63 



FlNE-ORAINED SAXONITE PARTLY ALTERED 



mpli s 1 


MgO 


SiOj 


Ft .< » 


Ti. Cr, \l. 
(Oxides) 


CaO 


Ign. Loss 


Da) Book \-2 


45.92 


12 40 


8.62 


L.06 


0.00 


1 23 











PETROGRAPHIC ANALYSIS 

Samplr — Day Rook A-l. (Fine-grained dunite.) The 
principal constituent of this rock is quite fresh 
olivine constituting about 95 per cent of the 
whole. The crystals vary in size between 0.1 and 
1.0 mm., averaging about 0.3 mm. 

Two thin stringers of talc were observed cut- 
ting through the hand specimen. No estimate 



Vnalysis by John Boyd of the United Feldspar and Mineral Company, Spruce Pine, 
North Carolina 
: ' Chemical analysis madi by TV A Minerals Testing Laboratory at Xorris. Note that 
samples Day npok \-l and V-2 are similar to specimens shown on Plate 5. 
Petrographic analysis made by W. Wurth Kriegel, Department of Ceramic Engineer- 
ing, University of North Carolina, Raleigh, North Carolina. 
Note that samples Day Book A-l and A-2 represent material as shown on Plate 5. 



OF North Carolina and Georgia 53 

can be made of the amount present; however, it 
is evidently small. 

The rock also contains about 1 to 2 per cent of 
chromite crystals scattered throughout the rock 
and a small amount of chlorite (less than 1 per 
cent). 
Sample™ — Day Book A-2. (Altered fine-grained saxonite.) 
The principal constituent of this rock is a quite 
fresh, low-iron olivine making up about 60 to 70 
per cent of the rock. The olivine shows a small 
amount of alteration to antigorite along crystal 
boundaries. The olivine crystals are rather 
small, varying in size between 0.05 and 0.3 mm. 

In addition to the olivine, the rock contains 
about 10 per cent each of long prismatic crystals 
of tremolite and nodular aggregates of talc. The 
tremolite crystals were found cutting through 
the olivine and also in the talc areas. Much of 
the talc contains inclusions of brown substances 
too fine to identify. Probably these inclusions 
are from the original rock from which the talc 
was formed. A few small remnants of a pyroxene 
mineral, probably bronzite or hypersthene, were 
observed. 

Scattered crystals of chromite (1 to 2 per cent) 
were observed throughout the rock. Surrounding 
the chromite are bladed crystals of chlorite. 
Chlorite was observed in other areas. The total 
amount of chlorite is estimated at about 5 per 
cent. 

P. C. E. VALUE 

Sample Day Book A-l has a P. C. E. Value of h36. 

THE NEWDALE OLIVINE DEPOSIT 

The Newdale olivine deposit is located one and three- 
fourths miles east of Micaville, Yancey County, North 
Carolina and one-fourth of a mile up Mine Branch, a 
tributary of South Toe River. The Clinchfield (C.C. & 
0.) railroad at Boonford is within one and one-half 
miles of the deposit. 



5fi 



Note that sampKs l).iv Book A-l and A-2 represent material .i^ shown on Plate 5, 



:. I 



KoRS 1 1 1:1 1 1 < »i.i\ im: I DEPOSITS 



Plate i i 






~F=I~ 



500 

=1 



CONTOUR INTERVAL 50 FEET 
DATUM MEAN SEA LEVEL 



NEWDALE DEPOSIT 



1000 FEET 



LEGEND 

fjv^j RELATIVELY UNALTERED GRANULAR OLIVINE 
SERPENTINI2ED DUNITE 
TALCY VERMICULITE FRINGE ZONE 
BIOTITE SCHIST 

£2 HORNBLENOE GNEISS 



of North Carolina and Georgia 55 

The dunite outcrops on two low hills, about 125 feet 
high, on each side of the road (see Plate 14). The 
formation is approximately 1800 feet long and 500 feet 
wide, most of which is barren or covered with small scrub 
growth. 

The olivine in this deposit is similar to that at Day 
Book in that it is extremely fine grained, pale green and 
yellow in color. However, scattered olivine crystals 
occur as large as 1 ! •> inches in diameter at several places 
throughout the formation. Near the middle portion of 
the formation large chromite octahedron crystals are 
rather conspicuous, but these, upon close examination, 
are found to be thinly spaced in the formation. No 
saxonite was observed. 

Along the southeastern part of this deposit there 
occurs a barren bluff in the dunite. Here the formation 
consists of a gray-green, inter-locking, crystalline, tough- 
type olivine. The grain size is larger than is usually 
found in this variety. 

One of the outstanding structural features of this 
deposit is the occurrence of smooth and straight vertical 
joints extending as much as 75 feet through the dunite. 
Expansion joints parallel to the surface (see Plate 15, 
Fig. A) are important structural features found in all 
the fine-grained dunites. The southwestern nose of the 
formation contains a fringe about 50 feet wide of soap- 
stone and interlocking anthophyllite asbestos. Most all 
the olivine occurring along the southern contact of the 
formation, is highly serpentinized and contains small 
areas of soapstone and anthophyllite asbestos. This 
deposit has suitable topography for two or more quarry 
sites in granular and relatively fresh olivine. It is esti- 
mated that the Newdale deposit contains 1,560,000 tons 
of relatively unaltered granular olivine and 5,090,000 
tons of serpentinized dunite above South Toe River. 



56 



Fors ii kitk < Olivine Deposits 



Plate r> 




Pioi 1:1 A Dunite outcrop showing thin overburden and expansion joints 

paralleling the surface. 




Fi..i in B Vermii ulite prospect exposing fault zone in dunite. Note the 
broken condition of the olivine, vertical fault face at left of 
picture, and slickensided talc (white) on boulders. 



of North Carolina and Georgia 



57 



chemical analysis 

Commercial Shipments of Olivine" 1 ' 



MgO 


SiO, 


Fe 2 3 


A1 2 3 


Ca( ) 


Ign. Loss 


Total 


47.81 


41.06 


7.27 


1.53 


.24 


2.43 


100.34 



Sample Newdale B-l has a P.C.E. value of +36. 

THE BAKERSVILLE OLIVINE DEPOSIT 

The smallest peridotite sampled in the Toecane area 
is the Bakersville olivine deposit located on White Oak 
Creek, one mile southeast of Bakersville, Mitchell County, 
N. C, and two and one-half miles east of the Clinchneld 
(C.C. & 0.) railroad station at Toecane. This deposit 
outcrops on the nose of a low hill south of White Oak 
Creek. While all of the dunite is not visible because of 
overburden, it is thought to be about 300 feet long and 
60 feet wide. The highest outcrop is only 30 feet above 
White Oak Creek. The olivine is medium-grain, granu- 
lar, and semi-friable with a high uniform chromite 
content. The most unique feature about this deposit is 
the presence of chrysotile asbestos which occurs as seams 
up to 6 inches thick and as individual fibers and clusters 
of fibers penetrating individual olivine grains. This 
deposit is estimated to contain 50,000 tons of relatively 
unaltered granular olivine above White Oak Creek. 

The deposits described above are by no means all the 
olivine deposits occurring in the Toecane area. However, 
they do represent the most important. Other deposits, 
such as the one near Loafers Glory, were not sampled 
because they had undergone extreme hydrothermal 
alteration, or because their location was inaccessible for 
commercial production. 



67 Analysis made liy John Boyd, United Feldspar & Mineral Company, Spruce l'm< 
North Carolina 



Forsti rite < >i.i\ i.\k Deposits 

CANTON-DEMOCRAT AREA 

The Canton-Democrat area is estimated to contain 
10,090,000 tons of relatively unaltered granular olivine 
and 69,230,000 tons of serpentinized dunite. 

This area extends as a belt about 10 miles wide, from 
Junaluska in Haywood County, to Barnardsville in Bun- 
combe County, a distance of about 30 miles. The center 
of this area is about 8 miles west of Asheville, N. C. In 
contrast to the usual rugged topography of western 
North Carolina, this area consists of large rolling hills, 
and wide-bottomed valleys. Drainage is directly or in- 
directly into the French Broad River which flows across 
the center of the area. 

The Asheville-Knoxville branch of the Southern Rail- 
way crosses the center of the area; and the Asheville- 
Murphy branch crosses the southwestern end. U. S. 
Highways 70 and 25, and 19 and 23 supplemented by 
State Highways 63, 197, and 209, are important routes 
for local commerce. Asheville, N. C, a few miles south 
of the area, is the largest and the most important city in 
western North Carolina, and because of its central 
location should become an important olivine-processing 
center. 

THE HOLCOMBE BRANCH OLIVINE DEPOSIT 

The Holcombe Branch olivine deposit is located one 
and one-half miles north of Democrat and 15 miles north 
of Asheville on both sides of Holcombe Branch in Madison 
County, North Carolina. The deposit is very irregular 
in outline, the maximum length being about 3,000 feet 
and the maximum width approximately 1,500 feet. The 
formation is somewhat broken up by faults and it con- 
tains several schist inclusions. The part of the forma- 
tion lying south of Holcombe Branch has been the most 
disturbed and contains a higher percentage of soapstone 
than does the northern half. Much of the northern half 
of the formation, especially the area near a small branch 



of North Carolina and Georgia 



59 



Plate 16 




CONTOUR INTERVAL 50 rttT 
DATUM ASSUMED 



HOLCOMBE BRANCH DEPOSIT 



LEGEND 
F: : :*:1 relatively unaltered granular olivine 
K#3 serpentinized dunite 

] TALCY VERMICULITE FRINGE ZONE 
BIOTITE SCHIST 
f^^ HORNBLENDE GNEISS 



60 Fobs i i ri it: < Olivine Deposits 

in the western part, is granular, and light yellow in color 
but apparently relatively sound (sec Plate 16). Chromite 
crystals art- rather conspicuous in the material and 
secondary minerals such as tale and chlorite are mostly 
confined to .joints. The surface part of boulders and 
outcrops are exceptionally friable. The parts of the 
Ilolcomhe Branch deposit that are fine-grained and 
yellow in color are similar in appearance to the Day Book 
and Newdale material. This deposit contains about 
:;..">:'. 1 1, nnn tons of relatively unaltered granular olivine 
and 1 T.onn, 1 1()0 tons of serpentinized dunite above Hol- 
combe Branch level. The granular material can be 
quarried or mined below Holcombe Branch level so that 
the economicallv recoverable olivine is about twice the 
amount given above. During early 1941 a new quarry 
and crushing plant was opened on the Holcombe Branch 
deposit which makes this the third active producer of 
olivine in the TVA region. 

PETROGRAPHIC ANALYSIS^ 

Sample — Holcombe Branch Dunite. The dunite (the 
Holcombe Branch area) is composed of a fine- 
grained laminated rock, varying in color from 
light yellowish green to dark green and almost 
I ilack. With the exception of occasional grains 
and crystals of chromite, no constituent but olivine 
is visible. 

.Most of the sections show a very fine-grained 
lock, the grains averaging 0.1 to 0.2 mm. in diam- 
eter, but with crossed nicols these are found to 
polarize together over considerable area, showing 
the grains to have been originally 0.6 to 1 mm. in 
diameter. ... In all cases the granules are sep- 
arated from each other by a thin development of 
yellowish or greenish serpentine. 



" Pratt and Lewis, op. til., p. 108. 



of North Carolina and Georgia 61 

Sample Holcombe Branch A-2 has a P.C.E. value 
of +36. 

THE DEMOCRAT DEPOSIT 

The Democrat deposit occurs in Buncombe County 
one and one-half miles southwest of the Holcombe Branch 
deposit. This deposit is one-half mile west of Democrat 
and extends from Ivy Creek southwestward for one and 
one-half miles. The formation is approximately 600 
feet wide at its northern end and tapers gradually to a 
narrow belt at the southwestern end. 

Most of the formation is covered with residual over- 
burden and in many places it is as much as 20 feet thick. 
However, adjacent to Ivy Creek the overburden is thin 
where the grade is fairly steep. The entire formation 
is serpentinized to such an extent that it is noticeable in 
all the outcrops. The dark serpentinized streaks obscure 
much of the chromite occurring as disseminated crystals 
throughout the olivine. The formation is cut by several 
large pegmatites, two of which are intermittently worked 
for high-grade feldspar (see Plate 17, Fig. A). Nickel 
silicate minerals occurring in cracks, joints, and as in- 
crustations are visible wherever there is a good exposure 
of the formation. Many years ago the formation was 
prospected for nickel minerals comparable to those occur- 
ring at Webster, N. C. 

This deposit is not well suited for the production of 
olivine alone, but it is worthy of attention because of the 
occurrence of nickel silicate minerals and disseminated 
crystals of chromite in the partly serpentinized dunite. 
This formation probably contains as much chromite as 
any in the entire olivine belt, It is estimated that the 
Democrat deposit contains 25,000,000 tons of serpen- 
tinized dunite and 2, 000, ()()() tons of relatively unaltered 
granular olivine above Ivy Creek level. 



62 



FORSTERITE < M l\ INK DEPOSITS 



Plate it 




Fh.i i;i A. Large pegmatite in dunite. Note small pegmatite in top contact, 
sheared talc above, and dark-colored serpentinized dunite in top 
right corner. 







Pigi isk R. — Dunite showing joint systems. 



of North Carolina and Georgia 



»;:; 



chemical analysis 

Highly Serpentinized Dunite 



Sample 60 


MgO 


Si< h 


Fe 2 ( ), 


Ti, Cr, VI, 
(Oxides) 


CaO 


[gn. Loss 


Democrat A-1 


45.39 


40.18 


8 . 94 


1.48 


0.00 


3 . 76 



.<il 



PETROGRAPHIC ANALYSIS 

Sample — Democrat, A-1. The rock appears to have been 
nearly all olivine before alteration, which is quite 
extensive at crystal boundaries. The olivine 
crystals vary in size between 0.1 and 1.2 mm. with 
an average diameter of about 0.4 mm. 

The alteration product of the olivine is chryso- 
tile serpentine with a small amount of antigorite. 
The chrysotile fibers are very short with a maxi- 
mum observed length of 0.1 mm. The serpentine 
appears to make up 10 to 15 per cent of the rock. 

Occuring with the olivine crystals are small 
(maximum of 0.1 mm.) crystals of a pyroxene 
which appears to be diopside. The pyroxene con- 
stitutes about 2 to 3 per cent of the rock. 

A small quantity (less than 1 per cent) of 
chromite and a negligible quantity of chlorite were 
observed. 

THE JUNO DEPOSIT 

The Juno deposit occurs one and three-fourths mile 
southeast of Leicester, Buncombe County, N. C, and 
about five miles northwest of Asheville. This is a serpen- 
tine deposit and is described here because it is probably 
the only occurrence of its kind in the entire olivine belt. 
The serpentine body is about 800 feet long and approxi- 
mately 60 feet wide with most of this area containing 
little or no overburden. The serpentine is dark green in 
color and highly fractured. A few fragments of the 



59 ( Ihemical analysis made by 'I V \ Minerals Testing Laboratory, Norris, I < mi. 
''" Sum pie I )( nion.it \-l similar to material shown in Plate 7, Fig. C. 
1,1 Petrographic analysis made by W. Wurth Kriegel, Department ol Ceramic Engineer- 
ing, University of North Carolina, Raleigh, N i 



6 1 Fors i erite < Olivine Deposits 

original olivine arc noticeable in some of the freshly 
broken pieces of the serpentine; the original chromite 
crystals, however, have heen unaffected and in some 
places arc rather conspicuous. Cracks and seams in the 
material arc filled with visible secondary magnetite. 
Talc and chlorite occur along many of the joints in the 
serpentine; also associated with the joints are impure 
chalcedony and possibly remnants of nickel silicate 
minerals. 

Outcrops of the Juno deposit are light gray in color 
and the weathered material is porous, with a specific 
gravity about one-third less than that of the fresh 
material. The weathering extends to a depth of about 
10 feet. The Juno deposit contains about 95,000 tons of 
"quarrable" serpentine. 

PETROGRAPHIC ANALYSIS'" 

Sample — Juno, A-2. The major constituent of this rock is 
antigorite serpentine. Of the original rock only 
pseudomorphs of a compact, moderate relief, low 
birefringent mineral remain. The properties are 
very similar to those of the antigorite with the 
exception of a slightly higher birefringence. Some 
of these remnants are stained by iron oxide. It 
might be that these are the mineral bastite formed 
from olivine. 

The black banding is the result of high concen- 
tration of small crystals of magnetite in those 
areas. A few crystals of chromite were observed. 

P. C. E. VALUE 

Sample Juno A-l has a P.C.E. value of 23 to 26. 

One-fourth of a mile west of this deposit, the state 
highway crosses a dunite body which is about 800 or 
900 feet wide. The material in this deposit is extremely 
serpentinized and weathered, so it is of doubtful value 
as an olivine deposit. Many other small and similar 
deposits occur in this same vicinity. 



Pi trographic analysis made by W. Wurth Kriegel, Department of Ceramic Engineer- 
ing University of North Carolina, Raleigh, N. C. 



of North Carolina and Georgia 65 

newfound gap deposit 

The Newfound Gap dunite occurs in Newfound Gap 
on the Haywood-Buncombe County line about 15 miles 
west of Asheville. This occurrence is five miles northeast 
of the railroad station at Canton, N. C. 

The Newfound Gap deposit is 1000 feet long and 250 
feet wide at its widest point (see Plate 18). The dunite 
occurs well above the local drainage system and it rises 
abruptly in a steep hill south of the state highway. The 
olivine in this formation is of a light green, granular, 
friable type with crystals and large blebs of chromite 
rather conspicuous throughout the mass. The olivine on 
outcrops is relatively sound and the hand specimen shows 
little alteration to serpentine. However, part of this 
formation, especially near the southern part, consists of 
brownish interlocking crystalline olivine probably of 
inferior refractory properties. Near the northeastern 
end where the highway crosses the formation the dunite 
is of the bluish tough variety containing chlorite. 

The topography of this deposit is well suited for a 
quarry and its location is within trucking distance of 
Canton or Alexander, N. C. It is estimated that this 
deposit contains 1,310,000 tons of relatively unaltered 
granular olivine and 6,640,000 tons of serpentinized 
dunite. 

Sample Newfound Gap A-2 has a P.C.E. value 
of f -36. 

THE HOMINY GROVE OLIVINE DEPOSIT 

The Hominy Grove olivine formation occurs two and 
one-fourth miles northeast of the railroad station at 
Canton, Haywood County, N. C. The eastern end of the 
deposit outcrops at the back of Hominy Grove Church. 
This dunite is approximately 2,000 feet long and 200 
feet wide with the long axis trending east and west. 
Most of this formation is covered with thick overburden, 
part of which was observed to consist of gravel and clay 



66 



FORSTERITE < OLIVINE DEPOSITS 



Plate is 




SCALE 



CONTOUR INTERVAL 30 FEET 
DATUM ASSUMED 



NEWFOUND GAP DEPOSIT 



LEGEND 



■X-3 RELATIVELY UNALTERED GRANULAR OLIVINE 



SERPENTINIZED DUNITE 



TALCY VERMICULITE FRINGE ZONE 



BIOTITE 5CHIST 



HORNBLENDE GNEISS 



of North Carolina and Georgia 67 

banks, probably terrace deposits from the Pigeon River. 
The eastern quarter of the deposit is best exposed and 
here the dunite, consisting of dark gray and green com- 
pact interlocking grains of olivine, outcrops in erosion 
gulches. This material in hand specimen shows indi- 
cation of slight serpentinization. A small area adjacent 
to the church was also observed to consist almost entirely 
of a fresh coarse-grained granular olivine similar to that 
occurring at Newfound Gap. This deposit is thought to 
contain about 20,000,000 tons of serpentinized dunite 
and 1,000,000 tons of relatively sound olivine. 

WEBSTER-BALSAM AREA 

The Webster-Balsam area is estimated to contain 
122,690,000 tons of relatively unaltered granular olivine 
and 334,000,000 tons of serpentinized dunite. This area 
contains the largest reserve of olivine of all the areas. 

The Webster-Balsam area is about 35 miles south- 
west of Asheville and extends from near the center of 
Jackson County northeastward to the Jackson-Haywood 
county line at Balsam Gap, with a length of about 15 
miles and a width of approximately 8 miles. The south- 
western end of the area is in the Tuckasegee Valley where 
low, rounded, hilly topography predominates and the 
eastern end is in the rugged Balsam Mountains. The 
Asheville-Murphy branch of the Southern Railway passes 
through the area from end to end, and the Tuckasegee 
and Southeastern branch line passes across Hie south- 
western part of the area. The Webster-Balsam area is 
well served by U. S. Highways Nos. 19 and 23 and 
numerous secondary highways. 

THE BALSAM GAP OLIVINE DEPOSIT 

The Balsam Gap olivine deposit is in the eastern part 
of Jackson County, one-half mile southwest of the 

Southern Railway station at Balsam. U. S. Highways 
Nos. 19 and 23 pass over the northern ^ml of this deposit. 



68 



FORSTERII E I U.l\ INK I DEPOSITS 




SCALE 
a&o soo 



CONTOU« INTERVAL 50 FEET 

DATUM ASSUMED 



BALSAM GAP DEPOSIT 



LEGEND 
RELATIVELY unaltered granular olivine 
B8&3 SERPENTINIZEO DUNITE 

TALCY VERMICULITE FRINGE ZONE 
BIOTITE SCHIST 
HORNBLENOE GNEISS 



of North Carolina and Georgia 



69 



Plate 20 



Hi : 






aH»-3& 



-'^-r^** 






I' 







Figure A. — Olivine deposit showing usual conical shape. 




Fiqube I'., olivine outcrop showing stunted vegetation common to man] 

deposits. 



Til FORSTERITE I OLIVINE DEPOSITS 

This deposit is about 2,000 feet long and approxi- 
mately . s <»<» feet wide at the widest point, with the long 
axis trending north and south (see Plate L9). The center 

of the deposit lies :->f)() feet above the nearby drainage 
system. This centra] portion, about 500 feet in diameter, 
rises as an almost sheer bluff (see Plate 20, Fig. A) from 
which huge boulders of olivine have rolled a considerable 
distance down the slope. These boulders are rather 
sound, and from a practical quarrying standpoint, are 
not classified as overburden. The overburden consists of 
residual boulder fragments and red soil derived from the 
olivine. 

The Balsam Gap deposit is composed of relatively 
sound dunite and saxonite. Most of the saxonite and 
altered materials are segregated near interior faults and 
the borders of the formation. Much of the Balsam Gap 
deposit is composed of light green, coarse-grained, friable 
dunite containing few accessory minerals with little 
visible serpentinization in the hand specimen (see Plate 
4, Fig. A). About one-fourth of the deposit is made up 
of coarse-grained and light green saxonite containing 
spots of talc (see Plate 4, Fig. B). Upon close exami- 
nation these talc blebs are found to be an alteration 
product of the bronzite crystals which are rather numer- 
ous in the saxonite. These bronzite crystals average 
about one-fourth inch in diameter but some crystals were 
observed with diameters of over one inch. At many 
points, especially near the borders of the coarse-textured 
dunite, there are small zones, often up to three feet wide 
and several times this in length, of magmatic segregated 
chromite intermixed with the olivine. An analysis of 
this material made at the Minerals Testing Laboratory 
shows that it contains 3.60 per cent of chromium oxide. 

The Balsam Gap deposit is broken into large blocks 
by numerous faults and joints. Partly because of its 
occurrence high above the local drainage level, weather- 



of North Carolina and Georgia 



71 



ing and clay have penetrated downward along joints and 
faults deep into the deposit. 

The Balsam Gap deposit contains about 17,330,000 
tons of relatively unaltered granular olivine and 32,860,- 
000 tons of serpentinized dunite above Scott Creek level. 

The first commercial production of olivine in the 
United States came from a quarry in the Balsam Gap 
deposit (see Plate 21, Fig. A). This quarry has been in 
operation since 1933 and has produced more than half 
of the olivine marketed from North Carolina. Another 
quarry, 750 feet to the northeast, has been worked in- 
termittently. The topographic features of this deposit 
are such that large quarries on several sides of the 
deposit can be operated simultaneously. 



chemical analysis 

Analysis of Commercial Shipments — Balsam Gap Olivine' 18 



Samples 


MgO 


Si0 2 


Fe 2 3 


CaO 


N 


48.45 


42.26 


8.82 


0.10 






S 


47.99 


41.60 


8.60 


00 









Relatively Unaltered Olivine 






Samples 64 


MgO 


Si0 2 


FeA 


Ti, Al, Cr, 
(Oxides) 


CaO 


Ign. Loss 


Balsam Gap A-l 


50.12 


39.90 


8.94 


1 . 86 


0.00 


0.49 





Slightly Altered Saxonite 






Samples 64 


MgO 


Si0 2 


Fe 2 0, 


Ti, Al. Cr, 
(Oxides) 


Cal ) 


1-11 1 ovs 


Balsam ( lap A-2 


47.00 


41.34 


8.78 


1 .22 


0.00 


I 57 



63 Chemical analysis by John Boyd, United Feldspar ami Minerals Company, Spruce 
Bine. North Carolina. 

M Sample A-l represents besl grade and Sample \-2 second gradi .i^ comrni rcially ship- 
ped. Chemical analysis made bj I \ \ Minerals resting Laboratory, Morris, Tennes- 
see. 



Plate 21 




*- -^ ♦**,•■ .w : > 



Figxjbe A. — Olivine Quarry. 



^ 



;t « 






- 1 "i . 




1 ><: l£iJ£? £•" ?T' 

Figube B. — Screening ou1 tines in olivine quarry after blast. 



of North Carolina and Georgia 



73 



Coarse-grained Dunite Relatively Unaltered Olivine 



Balsam Gap 

Sam pits' 1 '' 


MgO 


Si0 2 


Fe 2 O s 


Al, Ti, Cr, 

(Oxides) 


CaO 


[gn. Loss 


B-2.. 


50.14 


39.96 


10.70 


0.74 


0.00 


0.33 


C-l . 


49.31 


40.90 


9.58 


0.50 


0.00 


92 







Coarse-grained Saxonite Partly Altered 




Balsam ( lap 
Samples 65 


MgO 


S,()., 


Fe,0 3 


Al, Ti, Cr, 

(Oxides) 


CaO 


[gn. Loss 


B-3 


46.72 


43. IS 


9.10 


1 . 30 


0.00 


0.69 



Chromite in Dunite Relatively Unaltered Olivine 



Balsam Gap 
Samples 66 


MgO 


Si0 2 


Fe 2 3 


Al, Ti, Cr, 
(Oxides) 


CaO 


[gn. Loss 


B-l 


47.80 


38.62 


9.74 


5.90 


0.28 


0.31 







P. C. E, VALUE 

Sample Balsam Gap A-l has a P.C.E. value of +36 
to 38. 

Sample Balsam Gap A-2 has a P.C.E. value of +36. 



PETROGRAPHIC ANALYSIS 

Sample — Balsam Gap A-l. The rock consists essentially 
of light green olivine, showing very little altera- 
tion. The olivine crystals have a minimum size of 
0.1 mm., a maximum of 5 mm., and an average of 
about 3 mm. The crystals show less than normal 
shattering. The rock contains a very small 



'" Note thai Samples Balsam (lap 15-2 and C-l arc material Similar to t li.it in S| 

shown m Plate 4, Fig. A, Sample B-3 is similai i<> specimen shown in Plati I. 
and Sample B-l is material similar i<> specimen shown in Plate 1. Chemical ■ 
made at TVA Minerals listing Laboratory, Nbrris, rennessee. 

m Note that Samples Balsam (lap W-l ami I ' 1 an material similai In that in s| 

shown in I 'Ian I, Fig. A, Sample B-3 is similar to specimen shown in Plate I. 
ami Sample B-l is material similar m specimen shown in Plate 1. Chemical i 
made at TVA Minerals resting Laboratory, Norris, rennesset 
1,7 Petrographic analysis made by W. Wurth Kriegel, Department ol Ceramic Et 

ing, University ol North Carolina, Raleigh, North Carolina. 



lecimen 


I ,, B, 


inalj sis 


u emu n 


1,, B. 


inalj sis 


ijjini 1 1 



7 1 FORSTERITE OLIVINE DEPOSITS 

amount (less than 1 per cent) of chromite and 
magnel ite. 

The vein thai is observed in the hand specimen 
was found to be a fracture zone or band. Most of 
the fractures are filled with very thin seams of 
chrysotile and a few skeletons of magnetite. A 
few small crystals of chlorite were also observed 
in this zone. The vein makes up less than one 
pei - cent of the hand specimen. 

Sample — Balsam Gap A-2. The rock is quite highly al- 
tered. The principal minerals are olivine (about 
60 per cent), talc (20 to 30 per cent), antigorite 
(about 5 per cent) , and a small amount of chlorite, 
chromite, and magnetite. 

The olivine grain sizes vary from 0.05 to 3 mm. 
in diameter. About half of the rock is quite fresh, 
with little fracturing. The remaining half is quite 
shattered and shows alteration to antigorite. Of 
many crystals, only remnants remain from the 
alteration. A few of the grains show alteration 
across the grains and along the borders to ferro- 
mineral similar to bowlingite. Magnetite is found 
in the fissures with the antigorite. 

The talc appears to be an alteration product of 
a pyroxene of which only ghost cleavages remain. 
Several sections were found showing inclusions 
and typical bronzite schiller structure. The talc 
contains magnetite. 

A few small crystals of chromite surrounded by 
chlorite were found. Some of the chlorite is par- 
tially altered to antigorite. 

THE MIDDLETON DEPOSIT 

The Middleton dunite occurs approximately 1,200 
feet southwest of Balsam Gap deposit. The dunite is 
about 180 feet wide and 400 feet long, which makes it 
one of the smallest in the area. The main outcrop is on 
the crest of a steepsided ridge, about 300 feet above a 
tributary of Jones Creek. Most of the western half of 
the deposit is altered to soapstone. 



of North Carolina and Georgia 75 

Near the eastern extremity of this formation a small 
pit blasted into the fresh dunite has exposed a medium- 
grained, light green, friable olivine similar to that at the 
Balsam Gap deposit. Accessory minerals are almost 
entirely lacking in the exposed part of the deposit, except 
talc occurring in narrow veins. This deposit contains 
about 500,000 tons of relatively unaltered granular 
olivine and 100,000 tons of serpentinized dunite. 

DARK RIDGE DEPOSIT 

One of the more important peridotite formations in 
the Webster-Balsam area is the Dark Ridge olivine de- 
posit. It is located along the Southern Railway, one and 
one-fourth miles southwest of Balsam station, and 400 
feet east of Dark Ridge trestle. The deposit occurs as 
a north-south trending, lemon-shaped formation about 
2,000 feet long, and has a maximum width of 900 feet. 

The main part of the deposit forms an east-west spur 
(see Plate 22) which rises abruptly from the nearly 
valley floor to a height of about 400 feet. Dark Ridge 
Creek crosses the southern part, and Jones Creek bounds 
the northern end of the formation. The best exposures 
are on the north side of Dark Ridge Creek where a bluff 
of olivine rises steeply to a height 400 feet above creek 
level. Other good exposures occur along the Southern 
Railway cuts in the northern part of the deposit. 

This peridotite is composed of unusually coarse- 
grained dunite and saxonite. Two-thirds of the deposit 
consists of relatively unaltered dunite, forming a large 
lens-shaped core surrounded by saxonite. The dunite 
consists of relatively sound, dark green, granular, friable 
olivine. Giant shattered olivine crystals, as large as six 
inches in diameter occur throughout the core. To the 
unaided eye the material shows no signs of serpentini- 
zation. Small crystals of chromite are visible throughoul 
the dunite and at many places seams of massive chromite 
outcrop. 



76 



FORSTERITE < ILIVINE DEPOSITS 



Plate 22 




SCALE 
250 500 



COWTOU«» INTtBVAU 30 rtCT 
DATUM ASSUMCD 



DARK RIDGE DEPOSIT 



LEGEND 

RELATIVELY UNALTERED GRANULAR OLIVINE 

SERPENTINIZED DUNITE 
TALCY VERMICULITE FRINGE ZONE 
BIOTITE SCHIST 
^2 HORNBLENDE GNEISS 



of North Carolina and Georgia 



77 



Plate 23 



, 











Fkk're A. — Refractory grades of block olivine. 






Piguri B Crude forsterite olivine blocka ready for use in furnace walla 



78 



FORSTERITE OLIVINE DEPOSITS 



The saxonite occurs chiefly in the border zone of the 
formation or as small fault blocks within the dunite. 
The saxonite is partly altered to serpentine and steatite, 
especially near the contacts. However, most of it is 
relatively sound and is composed principally of coarse- 
grained, granular, dark green olivine. The bronzite 
crystals, often altered to talc, averages about one-fourth 
inch in diameter, and makes up 10 per cent of the rock. 

The Dark Ridge deposit is one of the most outstand- 
ing olivine formations in the entire olivine belt. It is 
not only one of the largest, but also one of the least 
altered. Most of the alteration has been of an auto- 
metamorphism character as no indications of pegmatitic 
intrusions are seen in the formation. The proportion of 
sound olivine is high in comparison to that of altered 
material in other deposits. This deposit contains 
16,550,000 tons of relatively unaltered granular olivine 
and 24,500,000 tons of partly serpentinized dunite and 
saxonite above Dark Ridge Creek level. 

The topography of this deposit is ideal for a large 
quarry so located that the olivine can be loaded directly 
into railway cars. 



.68 



chemical analysis 

Coarse-grained Dunite Relatively Unaltered Olivine 



Dark Ridge 
Sampli s 



A-l 



MgO 


Si0 2 


Fe 2 < » 


49. 69 


41.00 


9.74 



Al, Ti, Cr, 

(Oxides) 



it ;.s 



Ca< ) 



0.00 



Ign. Loss 



0.61 







Steatitized and 


Weathered Dunite 




Dark Ridge 
Sampli s 


MgO 


Si0 2 


Fe 2 3 


\\. Ti, Cr, 

(Oxides) 


CaO 


Ign. Loss 


\-7 






44.08 


43.60 


9 . f )0 


1.76 


1.23 


1.51 















68 Chemical analysis made hy TV \ Minerals Testing Laboratory, Norris, Tennessee. 



of North Carolina and Georgia 79 

p. c. e. value 

Sample Dark Ridge A-l has a P.C.E. value of 36 
to 38. 

Sample Dark Ridge C-6 has a P.C.E. value of 36 
to 38. 

PETROGRAPHIC ANALYSIS' ' 

Sample — Dark Ridge A-l. The olivine, which is the prin- 
cipal constituent of the rock, is quite fresh, with 
the majority of the crystals showing little or no 
fracturing ; however, a few of the crystals are 
badly shattered. A small amount of serpentiniza- 
tion has taken place around the borders of some 
of the crystals. The olivine crystals vary in size 
from about 0.2 mm. to about 2 mm. in diameter 
with an average of about 1 mm. 

A few large (about 5 mm.) crystals of bronzite 
were found in the rock. The amount would not 
exceed a very few per cent. 

The chromite in this sample is for the most part 
fine-grained (about 0.05 mm. in diameter) with a 
few large crystals (3 to 4 mm. in diameter). In 
all but one case the chromite is surrounded by 
olivine crystals. The one exception had a few 
small plates of chlorite around the chromite. The 
chromite comprises about 2 to 3 per cent of the 
rock. 

White talc was found on the surfaces of two 
small specimens. No estimate of quantity can be 
made. 
Sample — Dark Ridge C-l. This rock is composed of olivine, 
antigorite, talc, chlorite, and chromite and appears 
to have been nearly all olivine before alteration 
took place. 

The olivine composes about 50 per eent of the 
l'ock. About half of the olivine is unaltered and 
occurs in crystals of 1 to 2 mm. in diameter. Tin 1 
other half of the olivine is highly shattered and 
shows extensive alteration to antigorite. 



"Petrographic analysis made by W. Wurth Kriegel, Department ol Ceramii I n ineer- 

inu, University nf North Carolina, Raleigh, North Carolina 



SO FORSTERITE I M.I\ ink DEPOSITS 

The antigorite comprises 20 to 25 per cent of 
the rock. It is an alteration produd of the olivine 
and also from some of the chlorite. 

Talc makes up al><mt 20 per cent of the rock. 
The origin of the talc was not determined. Some 
sections show inclusions arranged in a pattern 
similar to those of pyroxene, however, no rem- 
nants sufficient to identify the source of the talc 
were found. 

The chlorite comprises about 10 per cent of the 
rock. Crystals were found throughout the rock 
but principally surrounding the chromite grains. 
Many of the crystals are partially serpentinized. 

Only a small amount of chromite was found. 
Sample — Dark Ridge C-6. The principal constituent (about 
90 per cent) of this rock is olivine. The crystals 
vary in size between 0.3 mm. (about 50 per cent) 
and 5 mm. in diameter with an average size of 1 
mm. A good deal of the olivine is shattered, show- 
ing parallel cracks. A small amount of alteration 
to what appears to be chrysotile was observed in 
some of the olivine crystals. 

A large per cent of talc was observed principally 
along veins ; however, isolated masses were found. 
A few crystals of olivine appear to have altered 
to talc. 

A vein of carbonate was observed in the rock. 
The carbonate appears to be an alteration product 
of the olivine and completely surrounds some of 
the small olivine crystals. 

Chromite occurs in the olivine and appears to 
make up from 2 to 3 per cent of the rock. A few 
crystals of chlorite were observed. 

THE ADDIE DEPOSIT 

The Addie deposit occurs about 35 miles southwest 
of Asheville near the center of the Webster-Balsam area. 
This deposit extends three-fourths of a mile northwest 
and slightly more than one mile south of the railroad 
station at Addie. It is 2,000 feet wide at its widest 
point which occurs one-fourth of a mile south of the 
station (see Plate 24). 



of North Carolina and Georgia 



81 



Plate 24 



2 >oo 




SCALE 
300 



CONTOU* INTERVAL iOFUT 
OATUM MEAN SCA L(V{L 



ADDIE DEPOSIT 



LEGEND 

RELATIVELY UNALTEREO GRANULAR OLIVINE 

SERPENTINIZEO DUNITE 
I,.- \\ T *LCY VERMICULITE TRINCE ZONE 
(HI BIOTITE SCHIST 
(JJj HORNBLENDE GNEISS 



82 Forsterite Olivine Deposits 

The Asheville-Murphy branch of the Southern Rail- 
wax- and also LI. S. Highways Nos. 19 and 23 (parallel 
to the railroad) cross the northern end of the deposit. 
Several secondary roads cross the deposit at various 

points. 

The Addie deposit is one of the largest in the Webster- 
Balsam area, and forms the eastern part of the great 
Webster-Balsam ring dike. This dike consists of a 
-erics of saxonite and dunite intrusions, which form an 
elliptical-shaped ring having a long axis of about six 
miles, and a short one of about three and one-half miles. 
The oldest dunites have been intruded by younger ones, 
and the whole mass later subjected to partial hydro- 
thermal alteration. The geology of this dike is extremely 
complex, the details of which are beyond the scope of 
this report. 

The Addie deposit, like others of the ring dike series, 
consists of a highly laminated dunite which on the 
weathered surface has an appearance of thin-bedded 
sandstone. These laminations, composed of concentra- 
tions of talc, chlorite, and other secondary minerals, are 
generally parallel to the formation contacts, and stand 
out as weather-resisting seams. Certain areas in the 
dunites, especially the later intrusions, suffered little 
metamorphism by hydrothermal solutions, and it is in 
these areas that the purest and highest grade olivine 
occurs. 

The northwestern part of the deposit (not shown on 
Plate 24) consists of two steep-sided hills divided by a 
small stream. A pegmatite along the contact has altered 
the southern half of the formation, on the western side 
of the stream, to a soapstone of sufficient purity to be 
classed as talc. The northern part of this section, west 
of the stream, is a steep barren hill containing a thin 
residua] clay underlain by two types of olivine. One is 
composed of gray-green interlocking crystals of medium- 



of North Carolina and Georgia 83 

grained olivine, partially altered to serpentine. The 
other is fine-grained, blue, highly laminated, tough 
olivine. Fine flakes of chlorite, scattered throughout the 
rock, greatly increase bonding strength. 

On the east side of the small creek, the olivine rises 
in a bluff about 100 feet in height. The southern and 
southwestern part of this bluff consists mostly of coarse- 
grained, tough, gray-green, interlocking olivine. Near 
the northern and western part of the bluff there is a zone 
about 75 feet wide of medium-grained light green, 
granular and semifriable olivine which contains few 
accessory minerals and shows little signs of alteration to 
serpentine. The northern and eastern part of the forma- 
tion, lying on the east side of the creek, has a rather 
heavy overburden, probably as much as 30 to 40 feet in 
most places. 

The main body of the Addie deposit, much of which is 
known as the Fisher property, lies south of Scott Creek 
and north of Ocher Creek. This part of the deposit is 
characterized by rugged topography made up of steep- 
sided and narrow riclges divided by deep valleys. 

Immediately south of the Fisher home is a steep ridge 
which rises from the valley floor and continues south- 
ward to Ocher and Scott Creek Gap. The northern half 
of this ridge, approximately 300 feet high, consists of 
good olivine which underlies an area about 1,500 feet 
long and 400 feet wide (see Plate 24). This olivine con- 
sists of both a coarse-grained, granular, interlocking 
crystalline type, and dark green, granular and friable 
material containing few accessory minerals except 
chromite. 

Near the middle of the Addie deposit there occurs an 
inclusion of mica-schist (see Plate 24). Surrounding 
this inclusion is a partly serpentinized dunite which con- 
tains many small seams filled with nickel silicate 
minerals. 



8 I FORSTERITE < )l.!\ INK DEPOSITS 

An abrupt bluff of olivine so feet high occurs adja- 
cent to Scott Creek a short distance east of the railroad 

station at Addie. This bluff continues as a long ridge 
southward for a distance of about 2,500 feet and has a 
width of approximately 500 feet (see Plate 24). The 
ridge is intersected by two small valleys at right angles 
to its long axis. Most of this ridge is underlain by olivine 
of the light green, coarse-grained, granular and friable 
type containing massive seams and disseminated crystals 
of chromite, the whole of which shows little indication 
of serpentinization. South of the ridge, the topography 
becomes rather steep and forms the Ocher-Scott Creek 
Gap, which is underlain mostly with a coarse-grained, 
interlocking crystalline type of olivine containing many 
small faults partly filled with vermiculite and asbestos. 

The southern part of the formation narrows to about 
H>0 feet in width and outcrops along a steep bluff over- 
looking Ocher Creek to the southwest. A gravel road 
passes along the center of this section of the Addie 
deposit ; the best olivine occurs between the road and 
( )cher Creek. This part of the formation outcrops as a 
sheer bluff in which all the olivine is highly laminated. 
This laminated olivine, however, has retained a part of 
its original granular, friable character, and serpentini- 
zation is only visible upon close examination of the hand 
specimen. The olivine outcrops on the northeastern 
branch of the gravel road contains exceptionally closely 
spaced vermiculite veins, some of which are as much as 
two feet in thickness. The part of the formation between 
the road and Ocher Creek offers several excellent quarry 
sites in relatively sound olivine. 

Much of the Addie deposit is nearly barren of vege- 
tation and contains practically no overburden. In the 
areas of granular, fresh olivine, the boulders stand well 
above the general surface. This deposit offers excep- 
tionally good quarrying possibilities, clue to the large 



of North Carolina and Georgia 



85 



reserve of high-grade olivine occurring adjacent to the 
railroad. 

The Addie deposit contains 28,350,000 tons of rela- 
tively unaltered granular olivine and 102,450,000 of 
serpentinized dunite above Scott Creek level. 

chemical analysis'" 

Relatively Unaltered Olivine from Addie Deposit 



Samples 


MgO 


Si0 2 


Fe 2 3 


Al, Ti, Cr, 
(Oxides) 


CaO 


Ign. Loss 


A-l 


48.80 


38.68 


10.88 


0.94 


0.12 


0.69 






B-l . 


48.64 


39.14 


10.40 


1.14 


0.08 


0.85 






C-l 


48.10 


39.58 


9.28 


1.24 


0.08 


1.14 






E-l .... 


46. S2 


37.40 


11.52 


1.60 


0.20 


1.77 







P. C. E. VALUE 

Sample A-l from the Addie deposit has a P.C.E. 
value of 36 and Sample E-l has a P.C.E. value of 35, 
which means the olivine has good P.C.E. value. 

Relatively Fresh Typical Saxonite from Addie Deposit 



Sample 


MgO 


Si0 2 


Fe 2 3 


Al, Ti, Cr, 
(( )xides) 


CaO 


[gn. 1 oss 


\-l 


46.40 


41.62 


9.28 


1.08 


0.20 


1 95 











Weathered and Steatited Dunite 



Sample 


MgO 


Si0 2 


1 , o 


Al. 1 i. Cr, 
(Oxides) 


('.,<> 


[gn. 1 oss 


O.C-1 . 


12.96 


1 1 . 86 


Kl 21 


1.76 


i) 22 


2 









( 



ii inu'.il .m.i 



lysis made by 1\ \. Minerals festing Laboratory, Norris, rennessee. 



36 



FORSTERITE I ILIVINE DEPOSITS 



*ARTIA SERPENTIMZKI) Dl'NITE KROM GARLAND DlLLAKI) 

Part of the Addie Deposit 



Sample 


MgO 

) 73 
46. c 


Ml 1, 


1', ■.. 1 


M. Ii. Cr, 
(Oxides) 


CaO 


[gn. Loss 


\-l 


W.94 


8 30 


1.86 


0.30 


2.22 






\-: 


41.34 


9.02 


1.1' 


0.32 


1.92 






B-l 


4> 


11 94 


s . 5 ; 


1.30 


0.32 


2.32 






B-2 


44.55 


40.78 


9.12 


1.28 


0.26 


2.71 






C-l 


45.24 


40.50 


8.40 


1.18 


0.30 


3.67 



PETROGRAPHIC ANALYSIS 

Sample — Addie E-2. The chief constituents of the rock are 
fine-grained antigorite serpentine and carbonate 
(dolomite or magnesite) occuring in nearly equal 
amounts. Throughout the rock are high-refrin- 
gent remnants of an orthorhombic mineral which 
likely is olivine. The particles are too small to 
determine their composition definitely. It is rather 
difficult to estimate the relative amounts of this 
mineral ; however, it is believed that it will amount 
to 15 to 20 per cent of the rock. 

A few badly shattered crystals of chromite are 
also present. 

Sample — Addie A-l. The principal constituent of this rock 
is olivine. It comprises about 90 per cent of the 
rock. The crystals of olivine vary in size between 
0.1 and 2 mm. in diameter with the majority about 
0.5 mm. Approximately half of the crystals are 
cracked. Many of the fissures are filled with ser- 
pentine. A few of the olivine crystals are partially 
altered to antigorite. Not over 2 per cent are so 
affected. The olivine is high in iron content as 
shown by the dark color of the rock and the 
presence of iron oxide with the antigorite. It is 



71 Petrographic analysis made by W. Wurth Kriegel, Department of Ceramic Engineer- 
ing, University of North Carolina, Raleigh, North Carolina. 



of North Carolina and Georgia 87 

estimated that the antigorite amounts to about 5 
per cent of the rock. 

About 5 per cent of the rock was found to be 
chromite which occurs in 0.03 to 0.05 mm. euhe- 
dral crystals. A few crystals of chlorite were 
observed. The latter occur at the olivine-chromite 
boundaries. 
Sample — Addie D-l. The principal constituent of the sam- 
ple is olivine. The crystals are cracked but are 
only slightly altered to antigorite along the crystal 
borders, with the exception of those crystals in 
contact with the blue veins cutting through the 
rock. These latter crystals are altered to anti- 
gorite and chlorite. 

About two-thirds of the vein material appears 
to be a mixture of antigorite, talc, and chlorite. 
The remaining third is largely bladed crystals of 
chlorite which penetrate into the margin of olivine 
crystals. 

The extent of the alteration of the material will 
depend upon the frequence of occurrence of the 
veins. There are only two in the hand specimens. 

The sample contains one to two per cent of 
chromite dispersed throughout the olivine. 

P. C. E. VALUE 

Sample Addie O.C. A-l has a P.C.E. value of 35 to 36. 

CANE CREEK OLIVINE DEPOSIT 

The Cane Creek deposit, three and one-half miles 
southeast of Sylva, N. C, is located one-half mile up Cane 
Creek, due west of Rocky Face Mountain. The deposit 
outcrops on the west side of Cane Creek as a roughly 
lens-shaped body trending in an east-west direction for 
about 1,500 feet. It has a maximum width of approxi- 
mately 300 feet. This deposit is a part of the Webster- 
Addie ring dike series. 

Most of the formation consists of dunite outcropping 
on two barren hills, divided by Mary Hooper branch 
(see Plate 25). A part of the formation along the 
southern contact, consists of a coarse-grained inter- 



ss 



FORSTERITE OLIVINE DEPOSITS 



'i. \ii: 25 




i — t i— i i=r 



SCALE 

280 500 



1000 rEET 



CONTOUR INTERVAL 50 FEET 
DATUM ASSUMED 



CANE CREEK DEPOSIT 



LEGEND 

RELATIVELY UNALTERED GRANULAR OLIVINE 

SERPENTINIZED DUNITE 

TALCY VERMICULITE FRINGE ZONE 



BIOTITE SCHIST 



HORNBLENDE GNEISS 



of North Carolina and Georgia 



89 



locking crystalline saxonite which has been highly 
laminated, and partly serpentinized. Talc blebs, altered 
from bronzite, are quite common throughout this part 
of the deposit. The central part of the formation con- 
sists mostly of coarse-grained, light green, friable and 
relatively sound olivine. Part of this friable material 
contains chromite crystals in such quantity that the 
weathered surface of the dunite has a black-spotted 
appearance. The formation contains very little over- 
burden except residual clay and a few residual boulders. 
Vermiculite- and chlorite-filled faults paralleling the long 
axis of the olivine formation are rather conspicuous. 

The Cane Creek deposit is rather small in size in com- 
parison with some of the other deposits in the area. 
This deposit is located one-half mile from the South- 
eastern and Tuckasegee Railroad and has suitable topo- 
graphy and sufficient reserves of relatively high-grade 
olivine to support two medium-sized quarries. It is 
estimated that this deposit has 1,800,000 tons of rela- 
tively unaltered granular olivine and 3,100,000 tons of 
serpentinized dunite above Cane Creek level. 

CHEMICAL ANALYSIS 7 " 





Serpentinized Saxonite 






Sample 


MgO 


Si0 2 


Fe 2 3 


Al, Ti, Cr, 

(Oxides) 


CaO 


[gn. Loss 


Cane Creek A-l 


44.82 


41.34 


9.44 


1.58 


0.30 


2. 35 





Relatively Unaltered Olivine 






Sample 


MgO 


S,< ), 


1 , ( » 


M. Ti, Cr. 
(Oxides) 


CaO 


[gn. 1 oss 


Cane Creek A-2.... 


48.78 


40.01 


L0.24 


0.48 


0.26 


0.92 







72 Chemical Analysis made by TV A Minerals Testing Laboratory, Morris, fennessi 



90 Forsterite Olivine Deposits 

P. C. E. VALUE 

Sample C'aiH' Creek A-2 has good refractory qualities 
because the P.C.E. value was found to be +35. 

PETROGRAPHIC ANALYSIS'" 

Sample — CANE Creek A-l. This rock is composed of 70 to 
80 per cent olivine, 10 per cent or more of talc, 
several per cent of anthophyllite and chlorite, and 
a small amount of antigorite and chromite. 

The olivine crystals vary in size between 0.1 and 
1.0 mm. in length. The crystals are all shattered. 
The fractures appear to be filled with antigorite ; 
however, it is so fine-grained that it is impossible 
to verify. Very few iron spots are seen along the 
altered edges, which would indicate that the 
olivine is low in iron content and approaches 
forsterite in composition. 

The talc is distributed throughout the rock and 
also is found in small nodules or clumps up to 2 or 
3 mm. in size. The talc forms the bulk of the 
filling and in places contains chlorite. 

The blue-black spots have a highly shattered 
chromite grain in the center surrounded by bladed 
crystals of chlorite. The chromite is very black 
even in small fragments and shows very few 
brown edges. It may be assumed that the chromite 
is high in iron. 

The anthophyllite may be the source of at least 
a part of the talc. 
Sample — Cane Creek A-3. This rock appears to contain at 
least 80 per cent olivine, 15 to 20 per cent of ser- 
pentine (largely antigorite), and 1 to 2 per cent 
chromite. 

The olivine occurs in fairly large crystals, many 
measuring 2 to 3 mm. in diameter. The crystals 
are all quite badly shattered, thus reducing the 
effective size. The fracture and spaces between 
the crystals show alteration to antigorite. Many 
of the olivine crystals are almost entirely altered 
leaving only remnants of the original crystals. 



73 Petrographic analysis made by W Wurth Kriegel, Department of Ceramic Engineer- 
ing, University of North Carolina, Raleigh, North Carolina. 



of North Carolina and Georgia 91 

The light green blades through the rock are 
mainly composed of antigorite with some rem- 
nants of olivine. Very little iron oxide is to be 
seen in the rock except in sections on the surfaces, 
which appear to be reddish in the hand specimens. 
Here, also, the olivine appears stained. 

The chromite occurs in small scattered grains 
usually surrounded by antigorite. The chromite 
is very dark, and shows brown only on the very 
thinnest edges. 

P. C. E. VALUE 

Sample Cane Creek A-2 has a P.C.E. value of +35. 

WEBSTER DEPOSIT 

The Webster peridotite is located about two miles 
south of Sylva, Jackson County, North Carolina. It 
extends from a short distance north of Webster, south- 
ward through the town to a point three-fourths of a mile 
south of the Tuckasegee River ; and then nearly due east 
for one mile to the Tuckasegee and Southwestern Rail- 
road (see Plate 26). The deposit is roughly crescent- 
shaped, and has a length of two and three-fourths miles, 
and maximum width of 1,800 feet. This is the largest 
peridotite body exposed in the ring dike. 

Most of the area consists of long, low, rolling ridges 
and wide valleys. However, the topography is quite 
rugged in the extreme eastern part, where the hills rise 
abruptly for about 250 feet above the valley floor. Just 
south of Webster, the rolling topography is again broken 
by a steep bluff 150 feet high, which parallels the 
northern bank of the Tuckasegee River. About one- 
fourth of the deposit, especially the uplands, is covered 
by transported clays, river gravels, and thick-residual 
soil. The best exposures of olivine are on the bluff over- 
looking the river. 

Apparently this formation is made up of a series of 
intrusions which have undergone various degrees of 
alteration, mostly caused by invading pegmatitic solu- 



92 



FORSTERITK Ol.I\ INK DhTOSITS 



lions. Along I lie eastern rim is a highly faulted and 
fractured zone in which the dunite is badly weathered 
and serpentinized. Several minor faults cut through the 
deposit in various directions, and on either side of these 
the rocks show signs of alteration. Typical of others in 
the ring dike, this deposit is highly laminated. 

Plate 26 




SCALE 

IOOO 



CONTOUR INTERVAL. SO FEET 
DATUM MEAN 5EA LEVEL 



WEBSTER DEPOSIT 



LEGEND 

[?X3 RELATIVELY UNALTERED GRANULAR OLIVINE 

SERPENTINIZED DUNITE 
[ . 1 TALCY VERMICULITE FRINGE ZONE 

BIOTITE SCHIST 

HORNBLENDE GNEISS 



of North Carolina and Georgia 93 

The Webster deposit consists, for the most part, of a 
medium-grained, fairly sound, granular, green olivine, 
which usually shows a slight amount of serpentinization. 
This rock occurs as a band occupying about 75 per cent 
of the western and southern half of the deposit, and ex- 
tends from just south of Webster to the eastern end of the 
deposit. Crystals of chromite have been concentrated in 
pockets and lenses within the band of dunite. Some of 
these concentrations, especially those near the eastern 
end of the deposit, have been mined to a limited extent. 
More chromite float is visible on the Webster formation 
than on any other dunite in the belt. 

Websterite, a variety of saxonite composed mostly of 
green diopside and brown bronzite, occurs as a band 
about 200 feet wide, just east of the unaltered dunite 
zone. This rock is rendered quite conspicuous by its 
bright grass-green color, extremely large grain size, and 
numerous bronzite crystals. (For analysis, see page 95.) 
The Websterite probably represents one of the later 
peridotite intrusions of the ring dike series. At present, 
this rock is of little commercial value. 

A badly weathered serpentinized olivine rock which 
has been fractured and faulted, occurs along the eastern 
rim of the formation. Nickel, occurring as silicate 
minerals, fills many of the cracks and faults in the rock. 
This nickelized zone, averaging 1.5 per cent Ni 71 extends 
nearly the entire length of the deposit, and attains a 
maximum thickness of 300 feet near the old Nickel Plant, 
just south of the river. 

The Webster deposit has several suitable quarry sites 
in the semi-fresh granular olivine. Probably the host of 
these sites is just south of Webster, along the bluff on the 
north side of Tuckasegee River. Most of the western 
end of this bluff is composed of a fairly sound olivine, 



74 (J. \V. Pawt-l, "Nicki-1 in North Carolina," Ei 1/ , Octobei 

1939, p. 35. 



n 



FORSTERITE < U.IVI.NK DEPOSITS 



with little overburden. Another good site is located in 
the extreme eastern end of the formation, near the 

Tuckasegee and Southwestern Railroad. Here the 
olivine is of the light green granular type, and is asso- 
ciated with pockets of chromite. Several other quarry 
sites are located throughout the formation. 

I rsing the Tucka^e.uee River as base level, the Webster 
deposit is estimated to contain 58,150,000 tons of rela- 
tively unaltered granular olivine, and 167,890,000 tons 
of serpentinized dunite. 

CHEMICAL ANALYSIS 

Relatively Unaltered Olivine 



Sampli 


MgO 


SiO s 


Fe 2 8 


\l. Ti. Cr, 
(Oxides) 


CaO 


Ign. Loss 


Webster A-l N 


45. 12 


41.38 


9.28 


1.26 


0.20 


1.97 



Relatively Unaltered Olivine and Chromite 


I 


Sampl 


MgO 


SiOj 


Fe 2 8 


Al, Ti, Cr, 

(Oxides) 


CaO 


Ign. Loss 


Webster G. C. B-l 36.41 


27.38 


12.48 


19.31 


0.22 


3.26 



Partly Altered Saxonite 



Sample 7 * 


MgO 


Si( >, 


r\ < > 


Al, Ti, Cr, 

(Oxides) 


CaO 


Ign. Loss 


Webster B-l N 


46.42 

1 


41.82 


9.12 


1.14 


0.18 


1.55 



Serpentinized and Weathered Dunite 



Sam pi 


MgO 


Si< >: 


Fe,0 3 


M, Ti, Cr, 

(Oxides) 


CaO 


Ign. Loss 


Webster B-l 


42.82 


; "" 04 


8.72 


1.14 


0.32 


9 17 







78 Chemical Analysis made by TV A Minerals Testing Laboratory, Xorris, Tennessee. 



of North Carolina and Georgia 



95 



Serpentinized Dunite 



Sample 71 ' 


MgO 


Si0 2 


Fe 2 3 


AI, Ti, Cr, 

(Oxides) 


CaO 


I Li ii . Loss 


Webster A-1 


44.08 


39.98 


8.00 


2.36 


0.20 


4.41 










Websterite from Webster, N. C. 


77 





MgO 



2>, i,<, 



SiO, 



55.14 



CaO 



s ;<; 



ho 



4.73 



Fe 2 3 



3.48 



A1,0 3 



i,i, 



H 2 



0.3S 



Cr 2 3 



0.25 



Websterite from Webster, N. C. 77 (Cont.) 


P 2 6 


NiO 


MnO 


Na 2 


Ti0 2 


Total 


0.23 


0.11 


0.03 


0.30 


Trace 


100.36 



P. C. E. VALUE 

Samples Webster B-1N and Webster B-l have P.C.E. 
values of +35, which is higher than would be expected 
from the chemical analysis. 



78 



PETROGRAPHIC ANALYSIS 

Petrography of Webster Dunite. 

This rock consists of an even-grained crystalline 
olivine, with more or less chromite disseminated 
through the mass in small grains and crystals. 
In texture the olivine varies from almost invisible 
grains to very coarse-grained masses, with occa- 
sional individuals an inch or more in diameter. The 
more common occurrences are somewhat coarser 
grain than loaf sugar. 

The least altered portions have a light to dark 
yellowish green or grayish green color, an oily to 
vitreous lustre, and an uneven, angular fracture. 
Weathering gives rise to all gradations of color 
from that of the fresh rock to the characteristic 
yellowish or reddish brown of the barren OUt- 



78 Chemical Analysis made by l\ \ Minerals resting Laboratory, Norris, Iuhiismi 

77 Websnrite analysis from Pratt and Lewis, op. cit., p. 97. 

78 Pratt and Lewis, op. cit.. p. 92. 



96 Forsi i i;i i e < )i.i\ ink Deposits 

crops. . . . Transparent colorless, allotriomorphic 
olivine grains constitute the mass of the rock. 
Chromite in scattering crystals or irregular grains 
is a constanl accessory .... 

In the great majority of cases, even when the 
hand specimens look perfectly fresh, the olivine is 
found to have altered somewhat to serpentine, with 
sometimes more or less talc, chlorite, etc. Hence 
the olivine grains are usually completely separated 
from one another by these secondary products. In 
many specimens, however, the alteration has been 
very slight; and, in a few sections, only traces of 
serpentine are to be found. The olivine is trans- 
parent and colorless, and exhibits typical optical 
characteristics. ... It is only in a somewhat ad- 
vanced stage of alteration that the corners become 
rounded and the section under the microscope as- 
sumes the appearance of rubble masonry. In the 
fresh specimens the olivine grains are often broken 
by irregular fractures. . . . With the beginning of 
alteration to serpentine, however, the increase in 
volume gives rise to stresses that greatly increase 
the irregular fracturing and frequently develop 
regular cleavage cracks in considerable num- 
bers. . . . Chloritization, a mode of alteration 
much less common than serpentinization, is well 
represented in portions of the Webster dunite. . . . 
Sample 7 ' 1 — Webster B-l N. The sample consists of 80 to 90 
per cent olivine, 10 per cent or more of enstatite 
and /or bronzite, several per cent of antigorite ser- 
pentine, a small amount of chromite, and a trace of 
chlorite. 

The olivine crystals are from 0.3 to 2 mm. in 
diameter, and are somewhat fractured. Antigorite 
surrounds the grains and fills the fractures. 

The pyroxene is largely enstatite ; however, a 
portion of it appears to be the ferruginous form, 
bronzite. The pyroxene is dispersed quite evenly 
throughout the rock. There is evidence of some 
serpentinization of this mineral. 



79 Petrographic Analysis made by W. Wurtb. Kriegel, Department of Ceramic Engineer- 
ing, University of North Carolina, Raleigh, North Carolina. 



of North Carolina and Georgia 97 

The antigorite does not appear to be concentrated 
in any large areas but fills around the other 
minerals in thin crystals oriented parallel to the 
fracture and crystal boundary lines. 

The chromite appears to be small in amount and 
rather low in iron content. It occurs in the olivine 
but is frequently surrounded by crystals of 
chlorite. 
Sample*" — Webster G. C. A-l. The sample consists of 50 to 
60 per cent olivine, 30 to 40 per cent antigorite, 
4 to 8 per cent chlorite, 4 to 8 per cent carbonate 
(likely dolomite), a small amount, perhaps one per 
cent of talc, one per cent or less of chromite, and 
a small amount of limonite. Because of the great 
variance of sections, the percentages are approxi- 
mations. 

The olivine appears to be rather iron free and 
must approach forsterite in composition. All of 
the crystals are shattered and few are not highly 
disintegrated. Only remnants of many remain. 

The carbonate appears to have replaced olivine. 
They showed no effervescence with hydrochloric 
acid. It is therefore assumed to be dolomite or 
magnesite. 

The serpentine is largely antigorite. The 
mineral appears to be the chief alteration product 
of the olivine. It surrounds all olivine grains. 

The chromite occurs in fairly large but badly 
shattered grains surrounded by chlorite. Chlorite 
also occurs in small isolated aggregates. 

P. C. E. VALUE 

Sample Webster G. C. B-l has a P.C.E. value of +36. 

Sample Webster B-l has a P.C.E. value of ^35. 

Sample Webster B-l N has a P.C.E. value of | 35. 

Several other deposits of granular olivine occur in 
the Webster-Balsam area, but are not described here 
because of their poor location in relation to transpor- 
tation. The best of these occurs near the headwaters of 
Cane Creek. 



80 Petrographic Analysis made In W Wurth Kriegel, Department ol Ceramic Engineei 
ing. University of North Carolina, Raleigh, North Carolina. 



98 FORSTBRITE Olivine Deposits 

ELLIJAY AREA 

The Ellijay area, about 15 miles long and 8 miles 
wide, is located apppoximately 55 miles southwest of 
Asheville, X. C. and a few miles east of Franklin, N. C. 
It extends from the northwestern part of Rabun County, 
Georgia, northeastward through Macon County, N. C, 
and into Jackson County, N. C. (see Plate 8). 

In genera] the topography is quite rough. The 
southwestern part of the area consists of high rounded 
hills and fairly wide valleys, while the northeastern part 
extends into the rugged Blue Ridge mountains. The 
entire drainage is by the Little Tennessee River which 
flows through the center of the area. 

Olivine deposits are scattered throughout the area, 
with the most important ones located within 3 miles of 
Ellijay Post Office. This report describes only those 
which are accessible to adequate transportation facilities, 
namely, Moores Knob, Ellijay Creek, Number 9, Corun- 
dum Hill, and Norton. These deposits contain an esti- 
mated 20,020,000 tons of relatively unaltered olivine, and 
56,340,000 tons of serpentinized dunite. 

The area is crossed by the Tallulah Falls Branch of 
the Southern Raihvay, and several federal highways. 
Many secondary roads make transportation fairly easy 
throughout the area. 

MOORES KNOB DEPOSIT 

The Moores Knob Dunite, three-fourths of a mile 
northeast of Ellijay, Macon County, N. C, is the largest 
deposit in the area. It is roughly lens-shaped, with 
minor and major axes of 1,000 and 3,000 feet respec- 
tively. Berry Prong of Ellijay Creek flows along the 
eastern and southern contacts of the formation. 

The deposit outcrops as a spur, wdiich rises abruptly 
from the north side of the creek to a height of about 200 
feet and continues northeastward at a steep grade to 
Amnion's Ridge, where it attains a height of about 400 



of North Carolina and Georgia 



99 



feet. Overburden is relatively light except in the north- 
western part of the area, where a thick red residual soil 
containing much soapstone float covers the rock. 

This olivine occurs as a dunite which has undergone 
some alteration. Most of the eastern quarter of the 
formation consists of relatively fresh, yellowish-green, 
coarse-textured, granular olivine; while that near the 
southwestern nose is fine-grained, light green, and some- 
what friable. The remainder of the deposit consists of 
steatizecl and chloritized dunite. This formation is esti- 
mated to contain 14,000 tons of relatively unaltered 
granular olivine and 42,000,000 tons of serpentinized 
dunite above Berry Prong of Ellijay Creek. 

Many years ago this deposit was worked for corun- 
dum. Recently these old workings have been reopened 
and many new shafts and tunnels driven into the forma- 
tion for the production of vermiculite. This mineral is 
quite abundant, occurring as veins and lenses throughout 
the deposit. 



,-i 



chemical analysis 

Relatively Unaltered Olivine 



Samples 


MgO 


Si( » • 


FeoOs 


Al, Ti, Cr. 

(Oxides) 


CaO 


[gn. 1 oss 


Moores Knob B-l 


49.48 


39.52 


9.2X 


1.12 


0.05 


0.08 




Chloritized Dunite 






Samples 


MgO 


SiO, 


Fe 2 ( 1 


Al, Ti, Cr, 
(Oxides) 


CaO 
0.10 

(t H 


[gn. 1 oss 


Moores Knoli \-l 


45.50 


42.06 


9.76 


I 06 
2.16 


1 13 


Moons Knob S-l 


46 60 


11 64 


7.50 


71 



P. C. E. VALUE 

Sample Moores Knob A-l has a P.C.H. value of 36-37. 



•i 



Chemical analysis made l>v TV A Minerals Testing I aboratory, Norris, fennessei 



LOO Forsterite Olivine Deposits 

ELLIJAY CREEK DEPOSIT 

The Ellijay Creek dunite — about one-half mile north- 
west of Ellijay Post Office, is just east of the point at 
which Merry Prong enters the main Ellijay Creek. The 
deposit is semicircular in shape and rises from creek level 
to a height of about 50 feet. This is one of the smallest 
deposits, and has an outcrop length of only 500 feet and 
a maximum width of 200 feet. The formation has been 
partly exposed on the southern side adjacent to the creek 
by recent vermiculite mining. 

The olivine occurs as a fresh, light green, granular, 
friable dunite, about half of which has undergone alter- 
ation. This deposit is estimated to contain 315,000 tons 
of relatively sound olivine and about an equal amount of 
serpentinized dunite. 

DEPOSIT NUMBER NINE 

Deposit Number Nine occurs one-half mile southwest 
of Ellijay Post Office and a short distance east of Ellijay 
Creek. This occurrence is about five miles east of Frank- 
lin, North Carolina. The deposit outcrops along the 
crest and on the north and south side of a low ridge 
which rises about 200 feet above Ellijay Creek. 

This deposit is heart-shaped with the long axis 
slightly more than 1,000 feet long and the width at the 
blunt end nearly 1,000 feet (see Plate 27). This forma- 
tion is made up of medium-grained dunite containing 
light green, fresh, friable olivine. The deposit is thickly 
intersected with small faults filled with exceptionally 
high grade, light green vermiculite. Some of these veins 
have been worked rather extensively. 

Near the southern extremity of this deposit, there 
occurs a concentration of massive chromite in small 
veins, but the most chromite occurs on the northern side 
of this formation in the form of disseminated crystals in 
a matrix of granular olivine. Little serpentine can be 
detected in the hand specimens of the dunite. 



of North Carolina and Georgia 



101 



Plate 27 




EHJE3^£iI 



SCALE 

300 600 



CONTOUR INTERVAL. SO FEET 

DATUM ASSUMED 



DEPOSIT NO. 9 



LEGEND 

£53 RELATIVELY UNALTERED GRANULAR OLIVINE 

8££3 SERPENTINIZED OUNITE 

[ 1 TALCY VERMICULITE FRINGE ZONE 

BIOTITE SCHIST 
YfA HORNBLENDE GNEISS 



102 



FORSTERITE OLIVINE DEPOSITS 



Although the deposit is not the largest in the Ellijay 
area, it may well he one of the most important because 
of its high grade and uniform olivine. The Number Nine 
deposit contains 5, 020, 000 tons of relatively sound olivine 
and 7,020,000 tons of serpentinized dunite above creek 
level. 



chemical analysis 

Relatively Unaltered Olivine 



Sample 


MgO 


Si0 2 


Fe 2 3 


Al, Ti, Cr, 
(Oxides) 


CaO 


Iun. Loss 


Number Nun \-l 


47.50 


38.94 


10.88 


1.36 


0.08 


0.89 


Number Nun- B-l 


47.96 


39.20 


11.20 


1.34 


0.22 


1.01 



P. C. E. VALUE 

Sample Deposit Nine B-l has a P.C.E. value of 35 
to 37. 

PETROGRAPHIC ANALYSIS 

Sample — Deposit Nine B-l. The rock contains 80 to 90 
per cent olivine. The crystals are all quite large, 
many measuring 2 or 3 mm. in diameter ; however, 
they are all quite badly shattered. The larger 
fractures are filled with chlorite. The smaller 
fractures are filled with chrysotile. Small areas 
of olivine show serpentinization to antigorite. 

Fairly large areas of chlorite are found in zones 
of fracture. A few chlorite crystals are found at 
the olivine boundaries, and they appear to be an 
alteration product of the olivine. 

Chromite occurs in many small crystals scat- 
tered throughout the rock. The average size is 
about 0.03 mm. in diameter with a few larger 
crystals about 0.4 mm. in diameter. All are sur- 
rounded by bladed crystals of chlorite. 



82 Chemical analysis by TVA Minerals Testing Laboratory, Norris, Tennessee. 

83 Petrographic analysis made by W. Wurth Kriegel, Department of Ceramic Engineer- 
ing, University of North Carolina, Raleigh, North Carolina. 



of North Carolina and Georgia 
Plate 28 



103 




SCALE 

100 300 



ioofeet 



CONTOUR INTERVAL 10 FEET 
0*tum ASSUMED 

MAP FROM N C GEOLOGICAL SURVEY. VOL I, PL. VI 



CORUNDUM HILL DEPOSIT 



LEGEND 

RELATIVELY UNALTERED GRANULAR OLIVINE 

SERPENTINIZED OUNITE 

TALCY VERMICULITE FRINGE ZONE 

BIOTITE SCHIST 

HORNBLENDE GNEISS 



lit 1 FORSTERITE < OLIVINE DEPOSITS 

THE CORUNDUM HILL OLIVINE DEPOSIT 

The Corundum Hill olivine deposit occurs six miles 
southeast of Franklin and one and one-fourth miles 
northwest of Gneiss. It forms a rounded hill a short dis- 
tance southeast of Evans Knob and one-half mile north 
of U. S. Highway 64. 

The Corundum Hill deposit is no doubt the most 
famous dunite formation in the entire country. The 
whole deposit is honeycombed with old corundum work- 
ings. It was here that corundum was first produced in 
the United States and that many of the fine corundum 
and gem specimens now in the National Museum were 
mined. 

This deposit is approximately 1,200 feet long and 
averages 500 feet wide. At its northeastern end and its 
southwestern end, this formation is rounded and blunt 
in shape, and in this respect is somewhat different from 
the other dunite formations occurring in the Appalachian 
area (see Plate 28). The formation contains several 
schist inclusions, especially near the northwestern con- 
tact zone. Some of these inclusions show evidence of 
having been faulted into place. Much of the deposit out- 
crops as a barren rounded hill. 

The Corundum Hill deposit consists entirely of dunite, 
part of which has been serpentinized. Near both ends 
of the formation the dunite is composed of coarse- 
grained, yellowish, granular olivine, much of which 
appears to be rather sound. Parts of the dunite, 
especially near the faults, are highly serpentinized and 
at a few places near the schist inclusion nickel silicate 
minerals are visible. 

The contact zones and many of the interior faults in 
the deposit are filled with vermiculite. This deposit has 
produced vermiculite intermittently since 1933. 

Note in the next analysis chart that the Corundum 
Hill olivine contains a rather high percentage of mag- 



of North Carolina and Georci a 



K).-) 



nesia which should make the material desirable for use 
in a chemical process. Two parts of the deposit offer 
good quarry sites in rather sound olivine. Corundum 
Hill deposit is estimated to contain 700,000 tons of 
relatively sound olivine and 6,970,000 tons of serpen- 
tinized dunite above creek level. 



.84 



chemical analysis 

Relatively Unaltered Olivine 



Sample 


m«o 


Si( ), 


Fe 2 3 


Al. Ti, Cr, 
(Oxides) 


CaO 


lull. 1 n« 


Corundum Hill A-l. 


49.35 


40.58 


8.30 


0.65 


Trace 


1.15 


Corundum Hill C-l ... 


48.62 


4 1 . 50 


7.52 


0.50 


Trace 


1.19 


Corundum Hill F-l... 


48.57 


40.20 


7.66 


1.94 


0.00 


1.42 



Partly Serpentinized Dunite 



Sample 


MgO 


Si0 2 


Fe 2 O s 


Al, Ti, Cr, 
(Oxides) 


CaO 


[gn. 1 oss 


Corundum Hill B-l .... 


45.46 


41.60 


8.46 


1.70 


Trace 


2.61 


Corundum 1 lill D-l 


47.52 


41.10 


8.70 


0.48 


Trace 


2.87 


Corundum Hill E-l 


47.70 


40. 'M 


8.06 


1.05 


Trao 


2.52 



P. C. E. VALUE 

Sample Corundum Hill A-l has a P.C.E. value of 

+35. 

petrographic analysis 

Sample — Corundum Dunite. "The fresh rock is <>r various 
shades of yellowish green, according t<> physical 
and chemical conditions. . . . Olivine IS the only 
abundant constituent of the rock, varying in tex- 
ture from very fine to medium coarse, with occa 



84 Chemical .ma I \ ms li \ I \ \ Minerals Testing Laboratory, Morris, Pennessei 
'" Petrographic analysis from Pratl and I ewis, op. ci;., p. 86. 



L06 



PORSTERITE OLIVINE DEPOSITS 



sioiial individuals measuring half an inch or more 
in diameter. . . . The olivine greatly exceeds all 
other minerals in abundance. It presents all de- 
grees of alteration to serpentine, only in rare cases 
appearing perfectly fresh. It is also rarely the 
case thai more than half of the mineral has been 
altered. . . . The olivine in the unaltered sec- 
tions ... is perfectly transparent and color- 
less. . . . [The grains vary] in size from 0.5 mm. 
to L2.0 mm. in diameter. The enstatite, which is 
found in most of the sections, occurs in nearly 
square or somewhat elongated sections of the 
prism zone . . . [and] in the great majority of 
cases it is also perfectly fresh " 

NORTON DUNITE DEPOSIT 

The Norton dunite occurs 14 miles south of Franklin 
and one mile north of the North Carolina and Georgia 
state line. This deposit occurs on the north side of Com- 
missioners Creek and one mile west of Tallulah Falls rail- 
road. The deposit forms a rugged hill overlooking the 
creek. 

This deposit contains little true olivine as it is com- 
posed mostly of anthophyllite asbestos and chlorite. The 
formation is nearly circular with a diameter of nearly 
500 feet. The top of the formation is estimated to be 300 
feet above creek level. 

The Norton deposit is estimated to contain 10,000,000 
tons of altered dunite above creek level. 

chemical analysis^' 1 

Amphibolized and Chloritized Dunite 



Sample 


MgO 


Si0 2 


Fe 2 3 


Al, Ti, Cr, 
(Oxides) 


CaO 


Ign. Loss 


Norton A-1 


39.04 


43.62 


10.24 


2.20 


1.32 


2.20 







P. C. E. VALUE 

Sample Norton A-1 has a P.C.E. value of 20-23. 



V", 



Chemical analysis by T\ A Minerals Testing Laboratory, Norris, Tennessee. 



of North Carolina and Georgia 107 

petrographic analysis^ 

Sample — Norton A-l. The rock appears to have been an 
olivine which has been highly altered. Remnants 
of what appears to be olivine were found. The 
principal alteration product is chlorite, making- up 
40 to 50 per cent of the rock. 

A fibrous mineral with typical amphibole cross- 
section cuts across the other minerals. The parallel 
extinction of the fibers would indicate that it is 
anthophyllite. The rock contains 15 to 20 per 
cent of this mineral. 

Small euhedral crystals of magnetite, estimated 

at about 5 per cent are distributed throughout the 

rock. A small amount of talc was also observed. 

There are many other olivine deposits occurring in 

the Ellijay area but the few described here are the most 

accessible and most typical. The best of the others occur 

on Higdon Mountain and in the headwaters area of 

Walnut Creek and Little Buck Creek. 

BUCK CREEK-SHOOTING CREEK AREA 

The Buck Creek-Shooting Creek area is estimated to 
contain 325,000,000 tons of serpentinized dunite and 
60,000,000 tons of relatively sound olivine. 

The Buck Creek-Shooting Creek area is located about 
100 miles southwest of Asheville, N. C. This area ex- 
tends from the central part of Towns County, Georgia, to 
near the Clay-Macon County line in North Carolina. The 1 
area, which is about 13 miles long and 7 miles wide, 
extends from Hiwassee, Georgia, to Rainbow Springs, 
N. C. The eastern part of the area is drained by the 
Nantahala River, the central by Shooting Creek, and the 
southwestern by the Hiwassee River; all of which are 
tributaries of the Tennessee River. 

The topography of the area consists of broad \ alleys 
and rolling hills for the central part and rugged moun- 
tains for the southwestern and northeastern part. Most 



87 Petrographic analysis byW, Wurth Kriegel, Departmem "i Ceramic I ngineering, 

University ot North ( '.iiolm.i, Raleigh, North Carolina. 



L08 FORSTERITE OLIVINE DEPOSITS 

of the eastern half of the Buck Creek-Shooting Creek 
area is above 1,000 feet in elevation. 

A branch line of the Southern Railway serves Hayes- 
ville, N. ('., located about three miles west of the central 
part of the area. U. S. Highways 64 and 76 pass through 
the area. 

BUCK CREEK DEPOSIT 

The Buck Creek dunite is located in the eastern part 
of Clay County, N. C, 25 miles east of Murphy, N. C. 
This deposit occurs two and one-half miles up Buck Creek 
and near the top of the rugged Nantahala Mountains. 
U. S. Highway 64 passes over part of the southern corner 
of the formation. 

The Buck Creek deposit is the largest single outcrop 
of dunite in the entire olivine belt. This deposit is 4,500 
feet wide at the eastern end and tapers to a narrow fringe 
at the western end. It has a length of about one and one- 
half miles. The topography of the deposit is rather 
rugged, as much of it is dunite cliffs. Part of the forma- 
tion rises to more than 700 feet above Buck Creek, which 
is carved as a gorge near the eastern part of the 
formation. 

The Buck Creek dunite consists of a series of in- 
trusions, some of which have undergone much alteration. 
The deposit is cut by many small pegmatites which aided 
in alteration of parts of the dunite into chlorite. How- 
ever, part of the deposit has remained relatively sound. 
Near the middle of the steep outcrop rising to the west of 
Buck Creek there occurs a zone about 250 feet wide of 
semigranular and partly friable olivine. This zone ex- 
tends from near Buck Creek westward to Smaragdite 
Hill, a distance of about 2,000 feet (see Plate 29) . Many 
of the samples taken from within this zone show only a 
small amount of alteration to serpentine and other 
minerals. 



of North Carolina and Georgia 



109 



A conservative estimate of 300,000,000 tons of dunite 
above Buck Creek is made for the deposit. The tonnage 
of rather fresh, granular olivine for this deposit is esti- 
mated at 52,820,000 tons. The Buck Creek olivine 
deposit is by no means the best one in the area, but it is 
important because of its enormous size and its location 
only 30 miles from the TVA Hiwassee Dam and only 10 
miles from one of the large Nantahala Power plants of 
the Aluminum Company of America. 

Other deposits of dunite occur in this area, mainly in 
the southern end. Some of the deposits in the vicinity of 
Hiwassee, Towns County, Georgia, contain fairly good 
olivine but they were not mapped or sampled, because 



Plate 29 




GONTOU" INTERVAL JOFEET 
OATUy MEAN SEA LEVEL 

TOPQ&WAPKT FROM NC GtOL lUBVE*. VOL I, PLATE V 



BUCK CREEK DEPOSIT 

LEGEND 

[Xvj RELATIVELY UNALTERED GRANULAR OLIVINE 

[££3 SERPENTINIZEO DUNITE 

TALCY VERMICULITE FRINGE ZONE 
Hill BIOTITE SCHIST 
^^ HORNBLENDE GNEISS 



1 1(1 



FORSTERITE OLIVINK DkI'OSITS 



of inaccessibility of the deposits from a commercial pro- 
duct inn standpoint. 



CHEMICAL ANALYSIS 



Sf.kp i:\timzkd Dun it?: 



Sample 


MgO 


SiOs 


Fe ,1 » 


Ti, Cr, \l. 
m fxides) 


Ca( ) 


[gn. Loss 


Murk Creek \-1 


46.52 


38.70 


10.70 


2.52 


0.56 


1.77 



P. C. E. VALUE 

Sample Buck Creek A-l has a P.C.E. value of 35 
to 37. 

PETROGRAPHIC ANALYSIS 

Sample*'-' — Buck Creek Dunite. The dunite in the unaltered 
portions is light yellowish green to dark oil-green 
in color and of medium to fine-grained texture. It 
frequently possesses a laminated structure similar 
to that of the Webster dunite, though this char- 
acter is by no means constant. In the various 
stages of serpentinization it becomes dark-green 
to greenish or brownish black. Black grains of 
chromite can generally be seen in the hand speci- 
men. On the weathered surfaces the dunite of 
this area is very similar to that of the other dis- 
tricts throughout the region, and presents the 
characteristic dark brown or dun color, except 
where very much serpentinized, and in such places 
it is nearly black. 

The microscopic character of the dunite is re- 
ported as follows : The rock consists essentially 
of olivine with small, variable amounts of green 
and colorless amphibole, chromite, and magnetite. 
In a great majority of the sections studied, altera- 
tion has given rise to one or more of the secondary 
products — serpentine, talc, chlorite, carbonates, 
and iron oxides. 



- s Chemical analysis made by TV A Minerals Testing Laboratory, Norris, Tennessee. 
89 Pratt and Lewis, op. cit., p. 73. 



of North Carolina and Georgia 111 

The olivine is perfectly colorless in the thin sec- 
tion and never shows crystal boundaries. It is 
generally cracked irregularly, particularly in the 
beginning of the change to serpentine. . . . The 
grains usually average from 0.5 mm. to 1 mm. in 
diameter, though isolated individuals of 5 mm. to 
6 mm. are sometimes seen. With the exception of 
occasional rounded grains of chromite, the olivine 
is entirely free from primary inclusions. . . . 
With the beginning of alteration the borders and 
portions along the cracks often become clouded 
with dustlike or granular segregations of iron 
oxides. 

The larger iron oxide spots are almost invaria- 
bly associated with lath-shaped or confused aggre- 
gates of chlorite. In some cases the olivine alters 
extensively to chlorite, which penetrates the grains 
generally along the cleavage cracks first, though 
frequently in diagonal directions, in long slender 
laths, sometimes passing uninterruptedly through 
two or three grains. 

Sample' 10 — Buck Creek A-2. The principal constituent of 
this rock is olivine, which amounts to about 70 
per cent of the rock. About one-third of the olivine 
is highly shattered and altered to antigorite. The 
olivine crystals vary in size from 0.3 mm. to 5 
mm. with the majority about 1.5 mm. to 2 mm. in 
diameter. 

Between 15 and 20 per cent of the rock is com- 
posed of antigorite, which is apparently largely 
derived from the olivine and is found cutting 
through olivine crystals. Sonic of the antigorites 
is derived from chlorite. The antigorite appears 
nearly iron free, thus indicating thai the olivine 
is a low-iron mineral approaching forsterite in 
composition. 

The chromite is much less in amount t han would 
appeal - from the hand specimens, and amounts to 

onlv a few per cent. The majority occurs as skele- 



80 Petrographic analysis by W, Wurth Kriegel, Department ol Ceramii Engineerin 
University of North Carolina, Raleigh,JN.*C 



li- Forsterite Olivine Deposits 

ton crystals in large crystals of chlorite. A lesser 
amount was found as small crystals in the olivine. 

The chlorite amounts to about l<> per cent of the 
rock and occurs only with the chromite as already 
mentioned. 

Thin black veins in the hand specimens appear 
to contain a high concentration of limonite. 

BURTON LAKE AREA 

The Burton Lake area occurs in a rugged part of the 
Blue Ridge Mountains about six miles west of Clayton, 
Rabun County, Georgia. This is a small area drained 
by the Tallulah River whose waters flow into the Atlantic. 
The area is crossed by U. S. Highway No. 76, and the 
Tallulah Falls Railroad passes through Clayton, Georgia. 

THE BURTON LAKE OLIVINE DEPOSIT 

The Burton Lake olivine deposit occurs near the 
western part of the area 12 miles west of Clayton, Ga., 
and 30 miles southeast of Murphy, N. C. ; U. S. Highway 
No. 76 passes over the deposit. This deposit is about 
2,600 feet long and 800 feet wide outcropping mainly 
south of the highway along the sides and crest of a sharp 
ridge. The part of the formation on the north side of 
the highway forms a steep slope facing away from the 
road. 

This whole deposit is of inferior dunite because of 
the high lime and iron content (see following analysis). 
Much of the dunite in this deposit shows serpentinization 
in the hand specimens. Near the central part of the 
western slope of the south ridge pyrite occurs in the 
olivine, which is the only occurrence noted in the area 
covered by this survey. This deposit contains several 
interior faults which have been partly prospected for slip 
fiber asbestos. Olivine in this deposit might be suitable 
for chemical use. 



of North Carolina and Georgia 



113 



CHEMICAL ANALYSIS 





Partly Altered Dunite 






Sample 


MgO 


Si0 2 


Fe 2 3 


Al, Ti, Cr, 

(Oxides) 


CaO 


[gn. Loss 


Burton Lake A-l 


45.54 


37.80 


13.44 


1.92 


0.18 


2.03 





Partly Altered Pyroxenite 






Sample 


MgO 


Si0 2 


Fe 2 3 


Al, Ti, Cr, 
(Oxides) 


CaO 


Ign. Loss 


Burton Lake B-l 


20.40 


50.80 


6.56 


1.78 


19.82 


1.29 



P. C. E. VALUE 

Sample Burton Lake B-l has a P.C.E. value of — 21. 

PETROGRAPHIC ANALYSIS 92 

Sample — Burton Lake B-l. The principal constituent of 
this rock is the pyroxene, diopside, which com- 
prises about 90 per cent of the rock. The rock is 
for the most part fine-grained, being made up of 
crystals 0.1 mm. or less in diameter with a few 
larger crystals about 1 mm. in diameter. The 
larger crystals show partial alteration to what 
appears to be antigorite. The smaller crystals 
show a small amount of alteration in a few fields 
to one of the horneblendes, probably actinolite. 

Scattered throughout the rock are many very 
small crystals of magnetite. It is estimated thai 
the magnetite constitutes from 3 to 5 per cent of 
the rock. A small amount of chlorite was also 
observed. 

THE LAUREL CREEK AREA 

The Laurel Creek area is located in the northeastern 
part of Rabun County, Georgia. The area is in moun- 
tainous territory on the eastern slopes of the Blue Ridge 



M Chemical analysis by TV A Minerals Testing I aboratory, Morris, rennesse< 
'■'- Petrographic analysis by W. Wurth ECriegel, Department ol Ceramic Engine* 
University of North Carolina, Raleigh, N C. 



1 1 1 FORSTERITE OLIVINE DEPOSITS 

near the point where the South Carolina, Georgia, and 
North Carolina state lines join. The entire area is 
drained by Wowoman Creek and other tributaries of the 
Savannah River which flows into the Atlantic. The area 
is crossed by U. S. Highway No. 28 and several good 
National Forest roads. The nearest railroads are at 
Clayton, Ga., 15 miles to the west, and at Walhalla, S. C, 
15 miles to the southeast. 

THE LAUREL CREEK OLIVINE DEPOSIT 

The Laurel Creek dunite occurs about one and one- 
half miles east of Pine Mountain, Georgia. This dunite 
body is about 2,500 feet long and averages about 1,200 
feet wide; and outcrops in the form of two rounded 
masses joined by a narrow neck (see Plate 30). The 
topography of the deposit is essentially bluffs of olivine 
facing Laurel Creek, except where several small tribu- 
taries of Laurel Creek have cut small gorges across the 
formation. 

The northeastern part of the Laurel Creek olivine 
deposit is the largest part of the formation and rises 
about two hundred feet above creek level. Most of the 
olivine is a relatively fresh and coarse-grained granular 
type ; however, it probably contains 20 per cent talc and 
anthophyllite asbestos which is uniformly distributed 
through the mass. With these minerals so thoroughly 
mixed with the olivine, it is doubtful that the deposit will 
be of value as a source of olivine in the near future. 

The western hill of this olivine deposit, covered with 
boulders and thin residual soil, rises about 100 feet above 
Laurel Creek. The southeast side of this mass is altered 
to a bluish serpentine but the central part is composed 
of relatively sound interlocking crystalline olivine. The 
material shows serpentinization along joints and cracks 
and it is likely that many of the individual grains are 
partly serpentinized. This part of the deposit shows few 
secondary minerals. 



of North Carolina and Georgia 



115 



Plate 30 




SCALE 

230 500 



CONTOUR INTERVAL JO FCCT 
D*TUM ASSUMED 



LAUREL CREEK DEPOSIT 



LEGEND 

RELATIVELY UNALTERED granular OLIVINE 
SERPENTINIZEO OUNITE 
TALCY VERMICULITE FRINGE ZONE 
BIOTlTE SCHIST 
p^j HOHNBLENOE GNEISS 



116 



FoRSTERITE OLIVINE DEPOSITS 



The Laurel Creek dunite deposit probably contains 
the best olivine in the slate of Georgia, as it shows less 
alteration than any other deposit examined in Georgia. 
The deposit has favorable topography for quarry sites 
and it is estimated that the formation contains, above 
Laurel Creek level, about 1,440,000 tons of relatively 
unaltered olivine and 17,650,000 tons of serpentinized 
dunite. 



CHEMICAL ANALYSIS 



93 



Serpentinized Dunite 



Sample 


MgO 


Si0 2 


FeiOs 


Al. Ti. C'r. 
(( hides) 


CaO 


Ign. Loss 


1 .mill Creek A-l. 


42.17 


43.92 


8.94 


1.40 


0.00 


3.94 



PETROGRAPHIC ANALYSIS" 

Sample — Laurel Creek B-l. Originally the rock was 
coarsely crystalline with crystals ranging up to 
3 mm. or 4 mm. in diameter. The two principal 
constituents were olivine and pyroxene (diopside) 
in the ratio of about 2 to 1. The rock is now high- 
ly shattered and altered so that the remaining 
crystals of olivine and diopside average about 0.1 
mm. in diameter. 

The olivine appears to have been fairly high in 
iron content as evidenced by iron oxide occurring 
with the antigorite. 

The principal alteration product is antigorite, 
which make up 30 to 40 per cent of the rock. 

In addition to the minerals discussed above, a 
small amount of chromite (less than 1 per cent) 
and a few crystals of talc were observed. 

P. C. E. VALUE 

Sample Laurel Creek B-l has a P.C.E. value of +36. 

To the northeast of the Laurel Creek deposit there 

occur several additional dunite formations which were 



93 Chemical analysis made by TVA Minerals Testing Laboratory, Norris, Tennessee. 

94 Petrographic analysis made by W. Wurth Kriegel, Department of Ceramic Engineer- 
ing, University of North Carolina, Raleigh, N. C. 



of North Carolina and Georgia 



117 



not mapped nor sampled because of their occurrence at 
points extremely inaccessible from a commercial pro- 
duction standpoint. 

South and west of the Laurel Creek deposit the dunite 
formations in the area have largely been altered into 
anthophyllite asbestos. 

Plate 31 



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